Added messages for users joining and parting from memos (issues #13 and #14).
Merge pull request #18 from Hydrothermal/dev

Dev
Merge pull request #19 from Hydrothermal/dev

Dev
Merge pull request #20 from Hydrothermal/dev

Added Procfile
Merge branch 'master' into dev
Changed client IDs from incremental to random

This makes it practically impossible to spoof another client by guessing
its ID and sending that to the server. The crypto module is used for
generating crypto-strong Base64 strings, which are then used as keys in
the clients object. CIDFct is used to shorten the IDs for readable logging.