Listen for fedmsg messages with a WebSocket.

Got the proof of concept working.  Still needs some work to make it awesome.

* Messages are received via websockets
* When they come in, we refresh the local cache automatically.
* If you are viewing a particular page, that page's results are visually updated.

Some ideas or things that need work:

* Can the user turn off websockets?
* Should we only update the cache for the page their looking at?  (instead of all pages like it currently does)
* Instead of requesting all messages, can we just slide in the latest message to the list instead of hiding it and replacing it with a new (almost identical) list?