Recording rewrite

I've been working on this for a while, and it's adapted from code that has been fairly well-tested on a wide variety of recordings. I've found it to do a more accurate job of combining multiple webcam files, and it should be more accurate in the audio as well.

Another key feature is that it does fewer re-encoding steps during video processing, which should both speed it up and hopefully improve quality. The settings on the VP8 encoder have been tuned somewhat as well.

Note that this *requires* a newer version of ffmpeg; an update to the check in bbb-conf is included. The current recommended version is ffmpeg-2.0.x. (Note that the matterhorn integration is *not* tested with this ffmpeg version!)