Mobile-friendly Profile Edit Pages

This PR dries up the profile editing pages and makes them display nicely on mobile.

- Use a partial for secondary nav
- Use client-side Javascript to emphasize active secondary nav link
- Show the gravatar, reduce the verbiage, make it pretty
- Use `:before` content to reduce form help-text redundancy
- Stack footer nav vertically on mobile

 
![screen shot 2014-11-04 at 2 12 35 pm](https://cloud.githubusercontent.com/assets/2289/4909180/601d6188-6471-11e4-81db-ab0648a6898f.png)

![screen shot 2014-11-04 at 2 18 08 pm](https://cloud.githubusercontent.com/assets/2289/4909182/669f0bba-6471-11e4-84ff-9f3cf5254894.png)

![screen shot 2014-11-04 at 2 19 54 pm](https://cloud.githubusercontent.com/assets/2289/4909189/746d0e7c-6471-11e4-9f59-c27e4165f98f.png)