Content Negotiation

[xentek]

A funny thing happened on the way to getting hyperdrive to support content negotiation…

• nearly the entire design of this gem has been overhauled
• no longer uses the Singleton mixin from the ruby stdlib in favor of a more flexible singleton approach using a "self-extended" Module
• extracts most HTTP logic into a mixture of custom and stock Rack middleware (including but not limited to Content Negotiation)
• fleshes out the DSL with more options for describing the API itself, as well as each Resource
• cleans up the specs and adds more test coverage to the remaining logic

It still has a few warts and completely favors json media types, but all-in-all, this branch gets hyperdrive ready for prime time.