Endpoint for creating CCXs on edX

[justinabrahms]

What's this PR do?

This adds an API endpoint to create CCXs on edX.

This is based on the branch #89. You can see the relatively small delta between those here: https://github.com/mitodl/ccxcon/compare/course-structure-query...create-ccx-endpoint

Where should the reviewer start?

courses/views.py

How should this be manually tested?

1. Create an OAuth client, grant, user, master course (with ccx enabled) on edx. You can see instructions for how to do this on #89.
2. Create an access token for a user on ccxcon. You can do this here

3. Issue the following curl command:

   curl -v -L -X POST \
    -H "Authorization: Bearer test-token" \
    https://localhost.daplie.com:8077/api/v1/ccx/ \
    -d "master_course_id=course-    v1:edX%2BDemoX%2BDemo_Course&user_email=verified@example.com&total_seats=30&display_    name=test_name_here"

   You may want to change some of these values, including:

   • test-token to the access token you generated above.
   • master_course_id to the id of the course you want to duplicate. You need to escape the +'s via %2B.
   • user_email to the user you want to be given access
   • total_seats for how many people you want to register
   • display_name to the name of the resulting CCX course.
4. Login as the user you chose for step 3 and see if you have ccx coach access.

   Any background context you want to provide?

This requires having Giovanni's branch gdm_feature_ccx_actual_apis_#119 setup on edX.

What are the relevant tickets?

Fixes #78

What gif best describes this PR or how it makes you feel?

[noisecapella]

I'll review #89 first since this PR branches off from that one

[giocalitri]

Just a couple of notes, but nothing blocking.

[giocalitri]

@noisecapella I reviewed this because it interacts with the CCX APIs on edx and I wanted to see how it worked.

[noisecapella]

Looks good to me :+1:

[giocalitri]

This can be merged. :+1: