Upgraded celery to 4.2

• Upgraded celery to 4.2
• Removed django-celery

Adding python3.8 support.

Adding python3.8 support.

FIX: Updated query according to model update in edx-platform

unable to download staff graded reports because there was recent change in program_enrollment model in edx-platform. so updated query and test accordingly to fix this issue.

Add student-key column to bulk grades download report

Add student-key column to the bulk grades download report. Populate it only for master's track students. Leave it blank for all other students

v0.6.6 Django22 Support

Added Django22 Support.

0.6.5

Fixes https://openedx.atlassian.net/browse/EDUCATOR-4821

0.6.4

• GradeCSVProcessor.save() should return something

0.6.3

• super-csv==0.9.4
• Call GradeCSVProcessor.save() super method with operating_user kwarg.

0.6.2

Update to edx-bulk-grades==0.9.3

Add comment and user_id to GradeCSVProcessor

• GradeCSVProcessor should now correctly pass comment and requesting_user to the edx-platform grades api