Support for running in AWS Lambda with no native extensions

[ghost]

I removed the dependency on OJ as that makes using this gem in AWS lambda more tricky.

I changed the dependency on rake and bundler to development only as they don't seem to be required for running when you use bundle install --deployment as you should when deploying to a serverless platform.

I also added support for resolution authorities which allows the Alexa service to try and match synonyms of words provided by the user to an actual slot value.

The only reason I was able to make these changes safely was because of your awesome test coverage! 💯 ❤️

[coveralls]

Coverage increased (+0.4%) to 94.331% when pulling a4899aef28acc5dbb25cd5fed20fc6240acfc7e1 on andrew-newell:master into fe03505e51239c890362e35d56a16148682a1366 on mulev:master.