[pvr] diskspace indicator in recordings view

@Jalle19, @xhaggi

Added diskspace indication with a progress bar in the recordings view.
Skinning is not really my thing, so hints are welcome ;-)

screenshot: 
![schermafdruk van 2014-09-25 13 41 24](https://cloud.githubusercontent.com/assets/2036512/4403843/4b1cf7b8-44a9-11e4-95b5-923efcc9006b.png)