Adding support for consuming WebHooks from Pusher
Use channel subscription for Twitter searches
The app now uses WebHooks to identify which channels
are being subscribed to by clients and thus which
keywords should be search for as Twitter filters.
This means that the updates aren't published on a 
single "stat" channel anymore, but instead are
published on the channel for that keyword.

Updated to use the Twit library instead of the twitter
one as IMO it's much better.

Channel name restrictions haven't been taken
into account as yet. Base64 encoding of the channel
name upon subscribing on the client and decoding
on the server (api) should fix this.