Trigger :message_dispatched when confirmed command is dispatched

[t33chong]

I'm using lita-confirmation in conjunction with lita-metrics, and I
discovered that commands requiring confirmation were not being logged
properly as valid commands. With this change, the :message_dispatched
event is triggered explicitly so that both the command requiring
confirmation and the confirmation itself are logged.

[coveralls]

Coverage remained the same at 100.0% when pulling 3c0b5ef on tristaneuan:trigger-message-dispatched into 0c1f991 on jimmycuadra:master.

[jimmycuadra]

I think the right way to fix this might be to change where that event is triggered in Lita. Instead of triggering it in Lita::Handler::ChatRouter#dispatch, it should probably be triggered in Lita::Handler::ChatRouter#dispatch_to_route, since that is called by #dispatch anyway. Can you think of any problems with that? I can't remember if there was a reason I didn't do it that way in the first place.

[t33chong]

Haha, probably because I was the one who introduced the trigger in the first place 😆 : litaio/lita#134

I've opened a new PR that moves the :message_dispatched trigger from Lita::Handler::ChatRouter#dispatch to Lita::Handler::ChatRouter#dispatch_to_route like you suggested:
litaio/lita#186