Set the page in the correct place.
Fixed accessibility labels are not always created in problems.
STUD-1524
Merge pull request #3451 from edx/waheed/stud1524-accessibility-labels-missing-in-problems

Fixed accessibility labels are not always created in problems.
Minor reword to server timed out message.
Merge pull request #3506 from edx/dcs/LMS-2562

Set the page in the correct place.
Merge pull request #3535 from edx/christina/typo

Minor reword to server timed out message.
Integrate event-tracking in to the LMS

Support incremental conversion of events from the old API to the new, the following initial changes are made so that we can validate the emission system:

* Emit events when an enrollment mode is changed.
* Use the new API for all enrollment events (including the new one).