 Clean up the Channel API and make it handle property changes properly.
 Clean up the Channel API and make it handle property changes properly.

 This removes some cruft from the API and adds some new useful
 properties. It also makes sure the logic in this is kept intact when
 the property changes. For example, changing the name of the channel,
 should unsubscribe from the old channel and subscribe to the new.

Cutehacks/qml-pusher