[#82591368] Allow CORS requests
[#82591368] Added specs for CORS
[#82591368] Update controller filters for CORS
[#82591368] Made the router more explicit in handling send_cart endpoint. Updated headers
[#82591368] ApplicationController: Update callbacks. Utilize headers across before and after filters in CommunicartsController
[#82591368] Go back to raising an exception with unverified requests since api requests aren't going through ApplicationController
Merge pull request #95 from 18F/82591368_allow_cors

82591368 allow cors