can specify last name using brackets
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
Change field validator rules for feedback session name
Merge branch 'Issue2386' of https://github.com/TEAMMATES/repo into Issue2427
Fix masquerade mode failure to edit
Revert fix for typo in error message.
Merge branch 'master' into Issue2417
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
add more files for instructor search purpose
add necessary methods in Db and logic for admin search for instructors