Add phone number to exhibit contacts; fixes #670

![screen shot 2014-06-03 at 8 15 37](https://cloud.githubusercontent.com/assets/111218/3162068/efeeda9e-eb31-11e3-9dcd-43f25b66a8ea.png)
![screen shot 2014-06-03 at 8 18 55](https://cloud.githubusercontent.com/assets/111218/3162127/6be23f92-eb32-11e3-8a04-833b69a7ea3d.png)

![screen shot 2014-06-03 at 8 18 42](https://cloud.githubusercontent.com/assets/111218/3162120/5d864b78-eb32-11e3-9a5e-e58d94a97b86.png)