BAT tracking issue

[tdooner]

Just got off a call discussing the eventual technical infrastructure that will be needed for the BATs, and some of it will likely be implemented in this repo.

A couple user stories came out as part of that discussion, and I'm going to write them down here in a very raw and unprioritized list.

As a user interested in joining a BAT

• I should be able to see a list of BATs
• I should be able to express my desire in joining a BAT
• I should see the calendar of BAT meetings

As a BAT team leader

• I should be notified when someone wants to join, so that I can send them a personalized welcome message
• I should be able to link important documents like agendas and minutes