Use single `grep` with `^` condition instead of `grep` + `cat` + `wc`

Technically just the true->false is needed. The `chown -R` was a first
attempt that didn't fix the bug, but it's a nice simplification.

This commit reworks the Vagrantfile for Nomad in order to support
straightforward testing on more than one operating system, whilst
retaining the ability to stand up a test cluster running Ubuntu.

The following changes are made:

- Scripts have been extracted from the Vagrantfile into their own shell
  script files, in order that editors lint them.

- All scripts have been edited to lint with no warnings or errors for
  their respective shells.

- Scripts are named according to the operating system and privilege
  level which they run. We prefer to run a whole shell script as root
  versus prefixing (essentially) every command with `sudo` or an
  equivalent.

- The Linux development box has been separated from the test cluster,
  removing some of the more gnarly (and less portable) logic. The Linux
  development box is still primary and autostarts.

- A FreeBSD target has been added. The base box works for both
  Virtualbox and VMWare Fusion.

- A target is added to the GNUmakefile to stand up a test cluster, using
  the default provider, or overriding the provider by setting the PROVIDER
  variable in make:
	- `make testcluster`
	- `make testcluster PROVIDER=vmware_fusion`

- Machines in the test cluster have Avahi configured for zeroconf
  discovery. Each machine can ping each other machine at `hostname.local`
  - for example `nomad-server02.local`, `nomad-client03.local`.

  * Change the GO_VERSION to match the correct upstream version from
    (https://storage.googleapis.com/golang/)

Had to use the hack from https://github.com/golang/go/issues/12443

Switch back to soft-float arm32 as armhf chips are backward compatible.

Makes running agents in vagrant without using `-dev` work.

`vagrant up` just works and only one VM is spun-up by default, however
there are up to 5x VMs available for cluster testing. `nomad-server%02d`
and `nomad-client%02d`.