Add an explicit BLYEvent object that solidifies some of the expected message fields.

This PR adds an explicit BLYEvent object that solidifies some of the expected message fields.

< also >
Add support for ping / pong win way of a 2 minute timer.
Add support for subscribing to presence channels.
Move channel event dispatch into the channel object.
Add NSNotifications for receipt of events at both the channel and the client level.
Add a delegate method to handle explicit receipt of events.
Removed deprecated delegate method support.
Explicitly listen for notifications from our reachability object.
Respond to ping events.
Object description methods.