Add the ability to respond to ACTION lines by creating linked issues in the same repo.

[nigelmegitt]

          I've often wondered if the bot should have the ability to respond 
          to ACTION lines by creating linked issues in the same repo.

Originally posted by @nigelmegitt in #71 (comment)

I think the complexity of this possibly factors against prioritising it, unless there's someone highly motivated to do it! Also worth noting that in the past, there was a W3C Issue Tracker and at least one of the bots (not sure if it was RRSAgent or Zakim) would respond to ACTION: lines by raising an issue on the configured WG tracker. If that behaviour still exists, it would need to be disabled somehow if another bot is logging the action.