OAuth workflow status and retry

Makefile

arkindex/dataimport/urls.py

arkindex/project/api_v1.py

arkindex/users/api.py

arkindex/users/migrations/0008_oauthcredentials_status.py

arkindex/users/models.py

arkindex/users/providers.py

arkindex/users/serializers.py

arkindex/users/tests/test_gitlab_oauth.py

arkindex/users/views.py