Submitted by: vendor, @maier

Escape hostname in agent encryption docs

Separate agent configuration into its own pages

I apologize in advance for the rather long PR, but unfortunately there
is not an easy way to break this up into smaller chunks. This separates
the agent configuration into smaller, more consumable pieces just like
the job specification.

Add Vault stanza everywhere

Adding a default ephemeral disk if it's not added by default

Document ephemeral_disk under group

Fixes GH-1915

Added docs for encryption

Update hcl to fix json parsing panic

Change the 0 timeout, interval validation to be more user friendly

Making Nomad TLS configs region aware

F vendor circonus