Allow cross-domain requests to API from browsers
Allow cross-domain requests to API from browsers

- Add "Access-Control-Allow-Origin: *" CORS header to all API responses
  to accept browser requests from any domain, not just the same as the
  API

Other minor updates:
- Add "Content-Type: text/json" header to the response if no content
  type is set by the user when returning from their endpoint
- Get rid of lingering 'login token' terminology

TribeMedia/meteor-restivus,yanlong/meteor-restivus,dandv/meteor-restivus,kaoskeya/meteor-restivus,azemoh/meteor-restivus,kahmali/meteor-restivus,jazeee/meteor-restivus