change ofQTKitVideoGrabber to use BGRA

also added accelerate framework to speed things up if it's running on 10.8
removed stray NSLog
updates to ofQTKitGrabber pixel copy

respect row bytes
respects deployment target for Accelerate.framework optimization
Merge pull request #1851 from obviousjim/bugfix-qtkitgrabber-pixelformat

change ofQTKitVideoGrabber to use BGRA