Pretty up the appointments listing with gravatar images

Before:
![screen shot 2013-10-21 at 5 29 21 pm](https://f.cloud.github.com/assets/202/1377181/3f06d244-3aa2-11e3-9e53-96bd56d228eb.png)

After:
![screen shot 2013-10-21 at 5 30 25 pm](https://f.cloud.github.com/assets/202/1377183/42036d72-3aa2-11e3-8b84-29a1e45c366f.png)