UI update

Another update for the UI !

Ok, so here is the changelog :
+ Added a circular progress bar when the filter is processing
+ Added stats : apps filtered / total apps
+ Moved 'category' filter outside of the collapsible filter frame
+ Changed clickable images for filters to checkboxes + added new strings (Translators : be careful ! A too long string will be cut...)
+ Various fixes
+ New icon for the 'restricted' filter
+ New card-like UI theme

![black](https://f.cloud.github.com/assets/3890441/1018340/d4d01eca-0c26-11e3-8467-f2928fcd707b.jpg)
![white](https://f.cloud.github.com/assets/3890441/1018343/d8a8ed38-0c26-11e3-801a-af587aea15bd.jpg)

(Sorry for the bunch of system apps in screenshots, I was on the emulator...)