[RFR] Use genuine bootstrap styling for the datagrid

- [x] switch to [sb-admin v2](http://startbootstrap.com/template-overviews/sb-admin-2/)
- [x] upgrade to bootstrap 3.3
- [x] remove custom ng-admin CSS code and let sb-admin do the work
- [x] Visual tweaks

![ng-admin](https://cloud.githubusercontent.com/assets/99944/5054950/2e8a37d4-6c5c-11e4-860e-662e773a8441.gif)