Adding slowcall!

So this adds initial support for a slowcall roster.

* !slow - On dorkbot mondays displays the attendee roster and possibly the absentee roster.  On non-dorkbot mondays displays when/where we pre-meet.
* !slow? - Always displays when/where we pre-meet.
* slow++ - On dorkbot mondays, adds the nick to the attendee roster, possibly removing them from the absentee roster.  On non-dorkbot mondays, groans slightly.
* slow-- -  On dorkbot mondays, adds the nick to the absentee roster, possibly removing them from the attendee roster.

It's a bit of a slog and should probably be in another file or even better probably a Cinch plugin/module...but it's a start.  It almost certainly can use some love to make it more ruby-esque.