Small improvements to SAO (performance/looks)

A picture is worth a thousand words I guess :

http://abload.de/img/screenshot_2014-10-0403ud5.png
http://abload.de/img/screenshot_2014-10-04roui3.png
http://abload.de/img/screenshot_2014-10-1066u3k.png

(I cheated a bit cause these were taken at 16 samples while the provided SAO.fx is only at 9 samples)
I removed the mipmaps as they were causing really visible flashing unfortunately. I'm now working on a 1/2 depth buffer for performance improvements instead (while the SSAO is rendered at 1:1)