Make our cookbook handling Berks 3.x compliant.

* Having the Berksfile be a bit of Ruby code that recursively runs
  berks on all out subdirectories is needlessly complicated, as berks will
  grab all the dependent cookbooks we need that are not listed in the
  top-level Berksfile in any case.
* Berks 3.x has shiny new dependencies.  Pull them in.
* Berks 3 has shiny new metadata requirements.  Add and/or fix them.
* Zap old copies of cookbooks we no longer use or care about.
Merge pull request #126 from VictorLowther/berkshelf-3.x-compatibility-and-fixes

+2 Make our cookbook handling Berks 3.x compliant.