Fix robot.respond bug which is occurred by unescaped robot.name

Hello team.

I have found `robot.respond` bug which is occurred by unescaped `robot.name`.

http://www.ietf.org/rfc/rfc1459.txt
IRC nickname is allowed to use any regex reserved characters, so `robot.name` should be escaped. I want to make an IRC bot whom I named `[^o^]`, but I can't it for this bug. :disappointed_relieved:

Could you review it? Thanks.