OO-2757: check keys and type in test course element to prevent error due to switch from test with QTI 2.1 and 1.2

no-jira: selenium tests for QTI 2.1 editor, 2 matches with different settings, scoring and with feedbacks

OO-2748: check assessment entry visiblity for show results, init the whole thing after suspend and cancel too

OO-2740: remove the email of the person leaving the group from the email to the person gaining access to it (patch S. Clemenz)