Addition of gitreload role for github Web hook course imports

Also support updating repositories such as python graders
from xqwatcher/xserver
Reference edxapp settings for repo directory
Reorder and use deploy.yml tasks
Move gitreload to use gunicorn configuration file
gitreload change log entry added
Add video upload defaults.
Merge pull request #1748 from edx/feanil/video_upload_settings

Add video upload defaults.
Merge pull request #1679 from mitodl/cg/gitreload

Addition of gitreload role for github Web hook course imports