Host github-btn.html in the app itself to prevet insecure HTTPS warning.
Don't send user command messages to remote IRC server as room message.
Fix sending ACTION messages to IRC server.

The ACTION message did not use to show up in IRC clients except for
webchat.freenode.net. node-irc already encloses 'ACTION foo' PRIVMSG
with \u0001. There was no need to enclose the ACTION message again
inside \u0001.