42 admin page

This PR adds admin flag to users table and allow admins to see a dashboard.

The dashboard contains users count, groups count, predictions count and matches between one day after and one day before.
![fwc_admin](https://cloud.githubusercontent.com/assets/357127/3163521/76c0ab5c-eb40-11e3-94f4-2f3a8180d1bf.png)