Added a method to the VideoPanelViewController that allows a Mat to
display on the panel.

Replaced the old *VideoFrame*Observers with new *Video*Observers. Added
the ability to observe the VideoMatriarch. An observer is notified when
a new video is set on the VideoMatriarch and the thumbnail of the video
is passed to the Observer.

Signed-off-by: Theo Chupp <chuppthe@msu.edu>