escape single quotes in optioninput (optionresponse) tags
STUD-893
dont update iframe src attribute if it is empty
STUD-1136
Merge pull request #2097 from zubair-arbi/zub/bugfix/std893-optionresponse

escape single quotes in optioninput (optionresponse) tags
Merge pull request #2147 from zubair-arbi/zub/bugfix/std1136-emptycoursevideo

dont update iframe src attribute if it is empty