Move to bundler for packaging

* new lib/casein/version.rb file which contains VERSION
* updated gemspec to include dependencies for testing
* added spec/rails_test_app for testing
* added a simple helper spec that passes
* new spec task
* added 1 helper spec (to get things started)
* dumped test tasks
* dumped jewelers tasks
* some whitespace cleanup (which makes the diff bigger than it needs to be)