Added session destruction functionality

Well a lot of moving parts.

It turns out the request.session (from express-connect) and redis are somehow decoupled. 

Have a nice weekend :)
The return above will only be called inside the callback's scope and not halt the rest of this function. You could end up in a situation trying to send a response twice. Additionally, session.destroy should return an error if the session doesn't exist, so you can take the above block out.