this regroups the calls of tmp func calls into one package.
the tmp pkg allows to store tmp files under a common directory for easier managment

Squashed commit of the following:
commit 74b674c01560c6b547e9cab5e8afb486f0fe7d6c
Merge: fc94b5714 66001525d
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Fri Nov 2 02:02:38 2018 -0400

    Merge branch 'remove_TMPDIR_docs' of github.com:tb3088/packer into remove_TMPDIR_docs

commit fc94b571428447aaf2e5171967c95cdf9e5c73ff
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Fri Nov 2 01:42:38 2018 -0400

    update tests to honor configured temporary directory

commit 5a562359f4937af506607dd96ed1c46426093f52
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Thu Nov 1 18:52:38 2018 -0400

    sync straggler to refactor. implement tests at packer/configfile instead of buried in docker.

commit 9d5a4a0935bfd049e2f8f50ad73e4455b42c9410
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Thu Nov 1 15:39:46 2018 -0400

    insert URL to GoLang API for os.TempDir()

commit fbae4c2e051898aecd8705e9d8a20353430ede23
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Thu Nov 1 07:41:29 2018 -0400

    revise documentation to match code

commit 3590fae8bd0afa92a161a49ed794ee32e357d583
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Thu Nov 1 07:21:59 2018 -0400

    refacter config_file. replace all hard-coded os.TempDir with wrapper

commit d5c5306a97b648ded06a8eb76ce728f07c9924f0
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Wed Oct 31 20:11:36 2018 -0400

    close massive file overwrite hole with TempDir

commit 0a72297da86089fbd07e4f7d9472a92fa4d1c733
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Wed Oct 31 01:06:00 2018 -0400

    adjust var declaration scope

commit 20f68228b6c372d984ea5b055cfc8bda9b110ac5
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Wed Oct 31 00:54:35 2018 -0400

    use mktemp() equivalent to create temporary directory

commit c73ebe3d8321664a2685a0baa8e441dd895b0db4
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Tue Oct 30 20:40:58 2018 -0400

    remove extraneous variable declaration, fix FOR loop

commit 63549b8bd745a0090b15ed0b0ebf644162db27db
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Tue Oct 30 19:30:44 2018 -0400

    match styistic convension with rest of docs

commit 976101074942db36f10d3a686d6d29ddb7c01926
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Tue Oct 30 19:08:39 2018 -0400

    revert dangling config file change

commit 95159afbc05eac96ed11c3183af5fb0abe2f2d5c
Author: Matthew Patton <matthew.patton@itgfirm.com>
Date:   Fri Dec 29 23:53:43 2017 -0500

    replace invalid TMPDIR variable wth PACKER_TMP_DIR.
    update ConfigTmpDir() to try common temporary paths first and
    only write to configDir() as a last resort.

commit 66001525d72de56a4cf9339b900c46f59bc6e91a
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Fri Nov 2 01:42:38 2018 -0400

    update tests to honor configured temporary directory

commit e9b6adefeae8c65eb8aa47fef38cbf0aa424338c
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Thu Nov 1 18:52:38 2018 -0400

    sync straggler to refactor. implement tests at packer/configfile instead of buried in docker.

commit 852113ed076e2d14e5dca6815ea680da1e2896bb
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Thu Nov 1 15:39:46 2018 -0400

    insert URL to GoLang API for os.TempDir()

commit 54add38d1d1c6e283cd444b367ed8bd49a5f3699
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Thu Nov 1 07:41:29 2018 -0400

    revise documentation to match code

commit 6b5b8f6d4edad0e187ca13d64ac4118f34eee643
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Thu Nov 1 07:21:59 2018 -0400

    refacter config_file. replace all hard-coded os.TempDir with wrapper

commit c22092c601c33484327674f322c7379fa41506d7
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Wed Oct 31 20:11:36 2018 -0400

    close massive file overwrite hole with TempDir

commit 7a730450916bf8e5dbc2a741ec233a49466ab7cc
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Wed Oct 31 01:06:00 2018 -0400

    adjust var declaration scope

commit 0f2933adb6f6922dfeab78a95371a444ec8918ab
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Wed Oct 31 00:54:35 2018 -0400

    use mktemp() equivalent to create temporary directory

commit d74839ede05dacf712b55a7bb48aec19fe6b007f
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Tue Oct 30 20:40:58 2018 -0400

    remove extraneous variable declaration, fix FOR loop

commit eb65416619437e4a3dec90277770803dd5b2281c
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Tue Oct 30 19:30:44 2018 -0400

    match styistic convension with rest of docs

commit acaa2b31ed463219c4ef099f351eec72406e2989
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Tue Oct 30 19:08:39 2018 -0400

    revert dangling config file change

commit e573fde668dcb418561e61535c1d68b2888f5b0f
Author: Matthew Patton <matthew.patton@itgfirm.com>
Date:   Fri Dec 29 23:53:43 2017 -0500

    replace invalid TMPDIR variable wth PACKER_TMP_DIR.
    update ConfigTmpDir() to try common temporary paths first and
    only write to configDir() as a last resort.

commit 39a9874afc9dea71b36753375fb7feb61ffecf69
Merge: 8a413cfe8 3315812c
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Tue Oct 30 18:19:26 2018 -0400

    Merge branch 'master' of https://github.com/hashicorp/packer into prestine

commit 8a413cfe83b0a70dbd99c32d936334ca5788ca9b
Merge: e07491de5 4e14710a
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Mon Oct 1 20:18:10 2018 -0400

    Merge remote-tracking branch 'upstream/master' into prestine

commit e07491de59cead0b337a7f57f4a6c625e1f560ab
Merge: 42610a35d a1fa35df
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Tue Aug 21 13:26:19 2018 -0400

    Merge remote-tracking branch 'upstream/master' into prestine

commit 42610a35d5ef65af8844a58ad70e2ec75262da6a
Merge: 5298142da 0d63cf7b
Author: Matthew Patton <matthew.patton@itgfirm.com>
Date:   Tue Jun 19 22:45:05 2018 -0400

    Merge remote-tracking branch 'upstream/master' into prestine

commit 5298142da6da95354844f201deeeef3c599e48b2
Merge: 7bb110bc7 9d973655
Author: Matthew Patton <mpatton@enquizit.com>
Date:   Mon Jun 11 15:10:09 2018 -0400

    Merge remote-tracking branch 'upstream/master' into prestine

commit 7bb110bc744c9797fcaec25a265d9b85a22d6d6b
Merge: a61c869ca 6189d66e
Author: Matthew Patton <matthew.patton@itgfirm.com>
Date:   Wed May 9 23:41:22 2018 -0400

    Merge remote-tracking branch 'upstream/master' into prestine

commit a61c869ca7268acf0e3b1e1fa7a8ee7feea65984
Merge: 098101dd9 4be5f072
Author: Matthew Patton <matthew.patton@itgfirm.com>
Date:   Fri May 4 10:13:04 2018 -0400

    Merge remote-tracking branch 'upstream/master' into prestine

commit 098101dd99f08b0ca110d33eff6904537c6d21de
Merge: fefaf0fa 554b2b4a


Author: Matthew Patton <matthew.patton@itgfirm.com>
Date:   Tue May 1 20:52:30 2018 -0400

    Merge branch 'EOL-handling' into prestine
Co-Authored-By: Matthew Patton <pattonme@yahoo.com>