[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: it's in the lower left corner now
![schermafdruk van 2014-08-31 00 31 25](https://cloud.githubusercontent.com/assets/2036512/4100449/4ac78938-3098-11e4-9aaa-2763fbe8ebca.png)