Moves, rename and add version to api controller.
moves api/email_controller to api/v1/email_requests
changes api route to support version
uses head as response instead of json.builder views
removes ApiController#error
adds protection agains requests with missing parameters
adds ApiConstraints class in order to simplify the use of versioned apis
Here is the reference for that:
http://railscasts.com/episodes/350-rest-api-versioning
removes unused views
Merge pull request #27 from darkseid/versioned_api

Versioned API and Renames Api::Email to Api::V1::EmailRequest