added NICK event to JSBot.parse()

Notable changes with this modification:

1. NICK is now a valid action listener.
2. NICK messages that don't conform to RFC 1459 are fixed (e.g. ```:old_nick NICK :new_nick``` would be changed to ```:old_nick NICK new_nick```.)
3. NICK events have a special ```event.newNick``` key. Additionally, ```event.channel``` will point to their new nick.

Do not merge this pull request until you are ready to also pull the corresponding depressionbot pull request, or depressionbot will break.