Support ruby 2.0.0
Update gems and hold activesupport at ~> 3.0.0

ActiveSupport ~> 3.2.0 works differently and the YAML can't render with it yet.
Meh. Just do all core_ext. Who cares?
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Merge pull request #51 from SmartReceipt/update_gems

Update gems and verify ruby 2.0 compat