can specify last name using brackets
temp push
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue2386
fix tests
temp push
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. separate student first name and last name in Feedbackreuslt CSV
2. update comment and tests
merge dev into Issue2427
user can only specify last name using "{}"
reset godmode.html
remove ambiguous intermediate variables
fix the test
add comment for getter of lastName in Student.java
[2427][Based On Dev]Give a way to specify student last name using braces

fixes #2427
fix tests