adding visibility toggle in contextualcomment.js
can specify last name using brackets
Merge remote-tracking branch 'origin/dev' into AccessControl
Merge branch 'master' into AccessControl
Change assert statements
Disable options that should  not be selected.
temp push
Fix some tests
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue2386
fix tests
temp push
Merge branch 'dev' into AccessControl
Merge branch 'master' into AccessControl
add backend support to visibilityoptions
Merge branch 'Issue2386' of https://github.com/TEAMMATES/repo into Issue2427
handle last name in CSV files
1. remove unnecessary method in StringHelper
2. fix all related tests
3. update FeedbackResultsDownloadActionTest for last name within braces
1.update student list download action test
2.update comments for feedbackSessionLogicTest
1. temp push
1. separate student first name and last name in Feedbackreuslt CSV
2. update comment and tests