Squashed 'bundle/virtualclass/' changes from 86a474e..c6cc5bc

c6cc5bc Move worker defination to teacher.php
bcd3479 updated worker code for screen share

git-subtree-dir: bundle/virtualclass
git-subtree-split: c6cc5bc551e682ddfea70d25c1bfa69d30509050
Merge commit '884f759d5e4a1144759fa0c3691a2a2fdba77270'