Next Protocol Negotiation

This PR has 
1. Readme and doc changes
2. examples - changes the TLS example to include NPN
3. server_conn.go - This is where I added the NPN. There are now 2 forms of ListenAndServeTLS - one with NoNPN and default (which has NPN).
4. server_test.go - old test functions' names changed. 
5. session.go - processSettings() was returning an error "Unexpected EOF" due to which communication with browsers was not working. Had to return nil. I had added this as a bug in tracker. It does not change anything in our implementation since we are not doing anything with the settings frame anyways.