Cross-Origin Resource Sharing

[mikaelsvensson]

Permit Javascript-based web applications hosted on other servers than the API server to send requests to the API.

Use https://github.com/cyu/rack-cors.

See also:

• http://dev.housetrip.com/2014/04/17/unleash-your-ajax-requests-with-cors/
• http://blog.rudylee.com/2013/10/29/rails-4-cors/
• http://stackoverflow.com/questions/29751115/how-to-enable-cors-in-rails-4-app