App to submit PR with annotations into a git repo

[nmanovic]

It is a very good practice to submit all annotations into a git repository. Now a user should download annotations and after that upload them into a git repository manually. It is necessary to implement a django application which will help with the task.

• Create new task dialog should have an additional optional field. If a git repository isn't specified it is OK. In this case all works as previously.
• Support GitLab and GitHub out of the box (use corresponding API to submit PR). Thus need to have a configuration dialog with GitLab/GitHub token, etc... Also GitLab/GitHub access can be setup using the app settings (can we configure app settings using web interface?)
• Need to have statuses: “all annotations were committed to the git repo” or “there are changes which are not committed yet”
• Probably it is a good time to implement a status for whole task (completed, in progress, open, etc...). Please review possible django/javascript apps which implement "issue tracker" functionality. Probably there is an open source app which can be integrated into CVAT as is and improve our dashboard.