Add command registration decorators
Add functionality to separate out commands given by a user.

Allows for:
	GorillaBot: command
	GorillaBot: !command
	!command
	/msg GorillaBot command
	/msg GorillaBot !command
	/msg GorillaBot GorillaBot: command
etc.
Merge branch 'rewrite' of https://github.com/mollywhite/GorillaBot into rewrite

Conflicts:
	bot.py
	command.py
	plugins/util.py