Relate towns and charities through presences

https://trello.com/c/J994ScXU/11-as-an-admin-i-can-add-towns-to-go-to-for-my-charity

![image](https://cloud.githubusercontent.com/assets/8646429/5095050/295f221c-6f34-11e4-892e-456cbba4afd0.png)

Huh, you learn something new every day!