Add trigger.raw and fix issue #310

This commit adds the `raw` property to the `Trigger` class, which is more accurate than using `bot.raw` to get the full raw line that triggered a function.

This also fixes issue #310: when Willie can't join a channel because it isn't identified, it joins as soon as it gets the message which should have given NickServ enough time to process identification. If not, each channel is retried 10 times with 6 second delays before giving a warning.