Added highlighting to selected filters in navigation drawer and tweaked styling

Changed drawer style to match the rest of the app. Also added highlighting so you can see what is already selected. Clicking an already selected filter will unselect it. I believe this makes it more clear that you can select only one project AND one context at a time. Previously I was confused when clicking on a project that the previously selected context was still active.

![2013-06-30 02 05 04](https://f.cloud.github.com/assets/792147/726999/7c7ee70e-e153-11e2-8731-ed1907095174.png)