Frebranch

- I have introduced a state monad (through a state transformer monad) to handle the channels initiialization. It is a change inducing a minor syntactical simplification in all examples. That is, the gsmap arguments disappear from the examples. 
- I've removed the channel from the Yesod foundation type (see Channelmap in Server.hs).
- Some minor stylistic changes here and there.