Rename chatserver to channel

Also pulls in most recent design doc changes, removes silly "That's what
she said" message that came in from the cowboy websocket server example
Merge remote-tracking branch 'bosshack/feature/rename_chatserver_to_channel'

Conflicts:
	priv/html_ws_client.html
	test/unit/channel_test.erl
Fix some problems with the merge. Remove unused functions in the tests.