Add in cross domain decorator

- Allows us to decorate api routes with things like `@crossdomain(origin='*')`
- Adds in test to the status feature, which is the only place this is being used currently
- Extends `core.response` — this felt like the right place
![](http://31.media.tumblr.com/fe1890ae29e9beb133b96e45fb60da31/tumblr_n3fsc43Ini1qfg8sio1_500.jpg)