User profile settings form

* Add User model form
* Add `settings.html` template using the form
* Add `privacy_controls.html` partial (which will also be used in popup from profile page)
* Add views
* Strip whitespace from first/last name in `User.clean`

In a future PR:
* Add Bootstrap so tab panels will work
* Add JS to enable/disable privacy controls and set hidden fields
I think they have to be hidden to support this checkboxless design:
![image](https://cloud.githubusercontent.com/assets/2162993/5186271/35b65e54-7493-11e4-9fdf-5cde973af8f8.png)