update chatserver_test for duplicate_username to take advantage of eunit macros
adds connect/2 and refactors add_user to do the check for duplicate usernames
DRYing
additional DRYing
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 branch 'master' of github.com:nrstott/chromechat
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.
removed now redundant connect method

This connect method was an artifact of where I was transforming this into the server and making a separate module for the channel instead of making this file into the channel.
adds server module to support multiple channels
implements server disconnect
join creates channel if it does not exist
adds meck dependency for mocking
incremental progress on server
adds ability for channels to be passed users instead of having to create them
From to _From in add_user since it is not used
extracts has_user function in channel to make it DRY
removes joining channel without user record, fixes broadcast join message for joining with user record
server sends the pid of the sender with the send message to channel
minor