Switch to using Librarian for cookbook management

[winhamwr]

Librarian looks awesome, and we should use it. Copy/pasting 3rd-party code in to a repo makes baby jesus cry.

It does add a ruby dependency though, which means folks will have to set up both a python and ruby environment. I think this is worth it, but I'm open to suggestions.

[winhamwr]

From the #chef IRC channel:

• yfeldblum, 12:46 -
  weswinham: ok, so what the integration does is it changes the cookbook_path to a new temporary path and installs the exact versions of the coobooks managed by librarian-chef into that temporary path (downloading/caching them if necessary)
  weswinham: so you wouldn't even need to run the librarian-chef command on the server you're managing, just hook the config script

So it looks like to use Librarian for cookbook management we'll need to add that ability to littlechef itself. That will include installing the Librarian gem and using Librarian's temporary cookbook folder on fix runs.