Allow cross origin requests

[AsafGartner]

Allows us to make api requests from other domains

[ifeins]

Looks ok, a few things:

• Extract the method implementation to CorsSupport, leave the after_filter :allow_cross_origin line in application_controller.rb.
• Have you tested it in any way? You can define a host for it locally in /etc/hosts: local.lunchtime.com and then in localhost make a cross origin post request.