Added a volumebar

Should close https://github.com/styxit/HTPC-Manager/issues/108

I'm not 100% percent happy about the bar, i would like to have it on the right side of the button groups, but no matter what i did it got unaligned or just plain skrewed up.. Still does the trick tho

![image](https://f.cloud.github.com/assets/1214134/2403269/b361104c-aa2c-11e3-958e-517b52ba970c.png)