Ruby cleanup, Berkshelf, Librarian, Test Kitchen configs cleanup, light refactoring

[jeffbyrnes]

Commit messages should say it all, but basically:

• Follow Ruby conventions better, courtesy of RuboCop
• More consistent TK config
• Test on Ubuntu 14.04
• Specify supported platforms in metadata
• Light refactoring to add memoization to node provider
• Update community cookbook endpoint

@jakedavis, @eherot, mind putting some 👀 on this?

[jakedavis]

Heh, give me explicit returns or give me death ;) nah, but that's cool, this looks great. +1.