Add media service to image rewriting

Waiting on a NGINX config change for this to go through.
Images from the media service need to be rewritten with `/media` prefixed as discussed with @phamann.

![Cameras](http://gifshost.com/012012/1327341659_lightning_caught_on_camera.gif)
Agreed. That would be more understandable. I was wondering about invalidating all the caches, but more importantly breaking any anything that has indexed or refers to our images.

@gklopper - do you have any thoughts on this?