Add achievement for posting with kotters

[kofkne]

Original Post from Moneyball (@evanpetzoldt)

To build on this idea... what if Weaselbot / Slackblast or whatever sent PAX on "missions" that were completable? Like:
Hey Moneyball! I noticed you haven't worked out with Sumo in a while / ever. I'm sending you on a mission to be included together in a backblast over the next two weeks.
And then get recognition in #achievement-unlocked if it happens

[jasheldo]

This is a fun idea and seems code heavy. But maybe I'm thinking of it wrong. It would require having a table in each region, say a kotters table, that lists kotters but also their buddies, when a notification was sent out and quite a few other dimensions. I may not be thinking of this right. But let me know if you agree on the approach.