cbabots: Get admin commands working

The bot will now poll an external URL for a set of commands to run.
README: Add simple description for authuser/authmessage
cbabots: Fix crash when no command file exists

Previously, when no bot control file existed, the bot would crash.  We
now check the length of the command array.
irc-botmanager: Optionally send a line on login

This changes the login message from a username/message pair to be
a raw IRC line.
Merge branch 'master' of github.com:xobs/cba-bot

Conflicts:
	cbabots.py