Based on ucfopen#612 and as an issue in ucfopen#619, this adds the `new_quizzes` and
`graphql` keyword endpoints in the requester module. Methods which
specify these locations will have the correct URL supplied by the
library in the `_url` parameter for the requester.

Calls from the `canvas`, `course`, and `new_quizzes` modules have been
updated to use they keywords rather than a formatted URL string.

All tests passing.

Rearrange to check for `_url` first, then assign the request url more
explicitely.