Update README.rdoc

Add travis-ci and code climate badges.
Update README.rdoc

Add gemnasium dependency status.
GFM Readme.
Consistent quotes.
Fix rake dependency.
Provide core extensions with Active Support.
Merge pull request #111 from heroku/active-support

Active Support
Bump version.
Added support for dependent picklists.

Sepcifying a second parameter when calling picklist_values will cause the function to only return picklist values that are valid for the specified controlling picklist value.
Cleaned up code a bit.
If value for the controlling picklist does not exist, return an empty array. Added more tests.
Cleanup
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Update comment.
Cleanup
Make test_bitset private.
base64 isn't need since we're just using unpack.