[WIP] Port notifications to Bootstrap and add filters, port hovercards

Fixes #4811, related to #4466 and #4424 
![](https://f.cloud.github.com/assets/3798614/2387364/2014e788-a936-11e3-9455-b7d9753b6f70.png)

Todo: 
- ~~port the aspect membership dropdown to Bootstrap and include it~~
- ~~javascript: Changes in notifications dropdown should include the notifications view~~
- ~~tests~~
- polishing