Blender Git Loki

Remove Video Proxy Resolution limitation

Height and width of video proxies was limited to multiples of 8 with
comment "JPEG requires this".

I could not find any resource that would confirm this to be the case
with FFMPEG and MJPEG codec.

I have looked in:
https://ffmpeg.org/ffmpeg-all.html
https://ffmpeg.org/ffmpeg-formats.html
https://ffmpeg.org/doxygen/trunk/structAVCodecContext.html

Reviewed By: ISS, sergey, sybren

Differential Revision: https://developer.blender.org/D6507