[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 2014-09-01 18 55 45](https://cloud.githubusercontent.com/assets/2036512/4111408/b6b34158-3207-11e4-8378-81acac8247b4.png)


and yes, I know it's likely typedef'ed as "long long" on everything out there ;-)