Removed STATIC_ROOT as it conflicted with STATICFILES_DIRS

Without this, I was getting `ImproperlyConfigured` which resulted in broken styles, among other things (see attachment).
![2014-08-25-113946_1916x1056_scrot](https://cloud.githubusercontent.com/assets/93686/4032231/05235692-2c6e-11e4-8a30-0a8e2dad96ab.png)

For the record, I'm using @almathew's settings, so if this isn't reproducible for you, ping me and I'll forward those. In fact, if you aren't able to reproduce this, it might be worth diffing the two sets to see what's different.