add mibbit.com link to connect to #hubot-irc channel
add mibbit.com link to connect to #hubot-irc channel

Spice-King/hubot-irc,miyazakijunichi/hubot-irc,Jaglag/hubot-irc,Jaglag/hubot-irc,BenoitZugmeyer/hubot-irc,nandub/hubot-irc,Spice-King/hubot-irc,BenoitZugmeyer/hubot-irc,nandub/hubot-irc,miyazakijunichi/hubot-irc