fix video quality issues
Created by: rjw57
This makes three changes which improve the video quality issues we've been observing:
- Use our own fork of galicaster which has a bug-fix for epiphan devices,
- Uses the force flag for the git Ansible module to make sure that the checkout succeeds in place of local modifications (e.g. the QR code plugin)
- Set the v4l2-split profile to use 1080p and 30fps.