COURSE_CERT_DATE_CHANGE was being called before saving the new data in
the course overview. The listeners were expecting to pull the data out
of the course overview, and thus were only right about half the time.
This moves the signal to trigger after the course publish signals are
handled.
The learner records feature had to be enabled/disabled via site-specific
configuration models, which is inconvenient for platforms that want to
disable this feature globally. Here, we introduce a
ENABLE_LEARNER_RECORDS feature toggle in the lms/cms settings that makes
it possible to disable this feature on all sites. Because this feature
toggle is set to True by default, this will not modify the behaviour of
existing platforms.
* INCR-250: Make compatible with Python 3.x without breaking Python 2.7 support --> openedx/core/djangoapps/programs
* INCR-250: Disable pylint warning and replace _f placeholder with actual name
* INCR-250: pylint format correction and fix over length line limit
