Adding mux GStreamer plugin libraries to Android (to enable video recording on Android)
Adding an option to limit the amount to disk used for saving videos
Adding an option to show/hide the REC button (allowing plugins to handle the recording in their own way)
Adding simple frame grab to file

- Altitude slider not showing up
- Continue mission not showing up in action list

For Video Streaming usecase, QGroundControl doesnt support changing of
Video Source or URI settings. Restart of QGroundControl application was
required for the changes to get applied. The issue is now resolved by
restarting the video receiver pipeline with new video source/setting.

Signed-off-by: lbegani <lalit.kumar.begani@intel.com>

Update the user model to a single controller instead of multiple

Added a bit more separation between the Toolstrip and the Toolbar

Fixed a pile of bugs as well