Implement CanvasAPI

[Thetwam]

CanvasAPI is a library created by UCF CDL that handles much of the heavy lifting when working with the Canvas API. Quiz Extensions has its own functions that handle Canvas API calls, but using a trusted library that has already handled all the edge cases would be much more reliable. It will also make Quiz Extensions' codebase smaller and easier to maintain.

CanvasAPI can be found here: https://github.com/ucfopen/canvasapi/