Any set orientation is overridden when RTMP publishing begins

[aaronzufall]

If I set any orientation before broadcasting using rtmpStream.captureSettings["orientation"], that value is overridden when stream publishing starts. I've found that this is due to lines 409-411 in AVMixer.swift:

if let orientation:AVCaptureVideoOrientation = AVMixer.getAVCaptureVideoOrientation(UIDevice.currentDevice().orientation) {
     self.orientation = orientation
}

These lines should either be removed, or something should check if an orientation was set through captureSettings. (Pull request)