Add support for passing device into docker driver

Fixes bug with display message logic due to deprecating GenericSource…

Fixes bug with display message logic due to deprecating GenericSource. Also added more test cases to cover a bunch more edge cases

Updated Troubleshooting section of Vault Integration docs

Updated Troubleshooting section of Vault Integration docs to mention the policy requirements for certain version combinations of Vault and Nomad, due to changes in Vault default policy and Nomad's vendored Vault lease renewal API.

Allow cross origin connections in ui

Handle multiple environment templates

`memory` default is 10, not 300

Fixes https://github.com/hashicorp/nomad/issues/3498

Change nodes to clients in the ui

In testing realized that Resources night not be present at all.  Testing this case caused panic. Added in a means to collect clean defaults in that case.

The current code would merge the job with the output of MinResources causing the nil to be replaced with MemoryMB=helper.IntToPtr(10).  When later `Canonicalize`d, the 10 would cause the default of 300 not to be applied. Running `Canonicalize` on the task itself guarantees that CPU, MemoryMB, and IOPS is set, so we can remove the Merge withMinResources.

jobs tests were sending invalid jobs

Verified by creating sample job and removing memory from resources

```
Task "redis" is "running"
Task Resources
CPU        Memory          Disk     IOPS  Addresses
3/100 MHz  976 KiB/10 MiB  300 MiB  0     db: **.**.**.**:20824
```

Update securing-nomad.html.md address flag example

The `nomad node-status` command incorrectly used the `-addr` flag; whereas the correct flag key is `-address`.

doc: fix some typos in the "Guides" documentation

[3503] adding consul-address flag to command.go

Fix panic on every run of the keyring command.

This change removes the flag token declaration within keyring.go
which caused a flag redefined panic on every command run as the
token flag is specified in the command meta.