Add host to polling message

The message for when an async task has finished has the hostname in it. This adds it to the polling message as well:

```
<job 390794962174.18311> finished on 107.6.24.140
<job 390794962174.31779> finished on 69.90.50.171
<job 390794962174.12328> polling on 69.90.50.172, 6840s remaining
```
Update intro_installation.rst

Corrected casing of Jinja2 in pip dependencies.
Updating v2 Role class code
Fixing up tests, removing some of the yaml error stuff from parsing

* moved old unittests for vault over to the new codebase
* reverted YAML error helpers and reverted the load() function
  in parsing/__init__.py, pending a rewrite of a new YAML loader
  class of some kind to encapsulate all of that
* fixed an error in in the module args parser regarding the shell/
  command argument parsing, where some additional arguments were
  being lost
Hook up the general parsing unittests and get them passing
Tell nose to include branches in its coverage reporting
Fix logic that prevents multiple action, local_action, and modules to be specified.
Adding in VaultEditor tests from old unittests
Merge pull request #9388 from mwarkentin/patch-2

Add host to polling message
Merge pull request #9394 from ronalexander/patch-1

Update intro_installation.rst