Availabilities "big board"

I'd like to be able to Chromecast per-city availabilities that remain for the current day. The idea is to apply a little "gamification" to encourage students to take the remaining mentoring spots.

![screen shot 2014-03-30 at 12 09 10 pm](https://cloud.githubusercontent.com/assets/55462/2561875/38d8e5e2-b82e-11e3-8c61-0c7b30b28340.png)

![screen shot 2014-03-30 at 12 09 24 pm](https://cloud.githubusercontent.com/assets/55462/2561876/3bc1f6a4-b82e-11e3-86cb-0184327745ab.png)