Add a cache! method and some tests.  Based on mbrandonw
Revert to mbrandonw version plus my own tests updated to match
Adjust cache! to use fetch semantics since that seems a better fit and allows for the :force => true option
Simplify cache! some more and make it behave correctly with nil values under cache
Merge with rails/jbuilder master
add option to ignore keys with nil values from generated json
Bump version, release new gem
Merge up master 0.6.0
Merge pull request #51 from rgarver/feature/add-caching

Add caching
Bump for caching feature
Fix the logic for testing if a block was passed in
Added a test for array! logic fix
Merge pull request #64 from jdeff/fix_array!

Fix the logic for testing if a block was passed into array!
Move the cache! method over to jbuilder_template where we can catch the partial! nested as well.
Merge pull request #66 from rgarver/feature/cache-with-partials

The new cache! method doesn't allow partial! calls to be nested
Change the #cache! method to use ActionView.cache so we can leverage controller.perform_caching and cache_digests in the future.
Some refactoring and better handling of nil cases for the output_buffer
Improve implementation of cache by not creating new builder.
Rename with_attributes to scope.
New style API with backwards compatibility.