Issue on ccx patch API api/ccx/v0/ccx/{ccx_id}/

[amir-qayyum-khan]

I was testing ccx PR Excluded admins, staff and coach of master course from max enrollment on stage.

1. I used api to update ccx attribute max_students_allowed to 1. I got success response.
2. But I was not able to verify new limit on max enrolment because ccx dashboard was allowing me to enroll all 10 student that I tried (seems like max students allowed are still 200 although api return this as 1)

Then

1. I fetched release branch rc/2016-04-12 from edX .
2. Then i set CCX_MAX_STUDENTS_ALLOWED = 1. In lms/env/common.py
3. And then I made new ccx and try to enroll more the 1 students. It only allowed me to add one student as expected.
4. Hence PR is working fine.

Then
I tested same api on devstack and i was able to reproduce issue which is api is not updating the max_students_allowed on running course.

My idea
I think api http{s}://{host}/api/ccx/v0/ccx/{ccx_id} is not working fine. It seems there is some cache related issues. After changing any ccx attribute it should update cache as well.

@giocalitri @pdpinch

[pdpinch]

@amir-qayyum-khan is this issue fixed by #256?