More clean admin login screen

A more clean admin login screen.
Which also behaves perfect on mobile devies.

![screen shot 2014-12-10 at 16 45 27](https://cloud.githubusercontent.com/assets/106335/5378689/24cd2500-808c-11e4-9a57-fa4d6db4d722.png)

(the bar on top is the bar of my browser :))