Canvas Integration

[JohnDamilola]

Hello @bradley-erickson, please help me review this new PR. This one has fewer and only relevant files in it and it now matches the up-to-date code with PMSS being used.

However, I still used a config.ini file for the canvas auth configuration details because I needed to automatically update the access token when it expires (after 1hr) and I figured that it was not safe/ideal to update the creds.yaml programmatically.

Other than that, I have applied the review comments you made on the previous PR.

[JohnDamilola]

Here are the new changes added after the last review:

• Removed class-based Ajax calls for Canvas and Implemented authorization protocol similar to Google
• Added Canvas course assignments API methods and routes
• Abstracted the raw_google_ajax and raw_canvas_ajax to one single function that can accommodate other future LMSes
• Cleanup code (removed unused comments, add missing imports, etc.)
• Ensured new tokens are generated for Canvas when there is a 401 error
• Streamlined LMS setup based on selected LMS in the creds.yaml
• Fixed text alignment issues

[pmitros]

Holistically, this looks very good and quite close.

I left many comments throughout the code, mostly focused on:

• I'd like to understand the security model (not just as me right now, but as a future code reader). A lot of handlers don't check for auth, and it's not clear when / how things authenticated.
• This should run through pycodestyle and pylint. There are a lot of details those will catch
• Most functions should have docstrings, and in many cases, we need better variable names

Aside from understanding security model, I have no major comments; just the kinds of polish generally needed for a final merge.

Thank you for the contribution.