per-app dashboards (bug 928160)

/comm/app/APP_SLUG/

- Start indicating version next to app name.
- Clicking on the app name leads to per-app dashboard, clicking on "XX Notes" leads to threawd.
- Order threads in the per-app dashboard by '-created', not '-modified'.
- Various prettifying (remove borders, remove extra padding on bottom of note container)

**Per-app**

![screen shot 2013-10-21 at 1 26 30 pm](https://f.cloud.github.com/assets/674727/1376109/2bf5620a-3a8f-11e3-993f-89093dffb08e.png)

**No threads**

![screen shot 2013-10-21 at 1 35 47 pm](https://f.cloud.github.com/assets/674727/1376191/6c7a04f6-3a90-11e3-8d96-188ad1d99dc9.png)


**Invalid slug given**

![screen shot 2013-10-21 at 1 26 23 pm](https://f.cloud.github.com/assets/674727/1376110/2e80c3d4-3a8f-11e3-8932-bafe681cbcfb.png)