Merge branch 'master' of https://github.com/TEAMMATES/repo
edited/added test cases to improve coverage
removed a TODO

Parameters not expected to be null and even if they are, no damage is
expected.
defense against null parameter

assertion to check for null parameter
add test cases for updateSession
improved validation checks in IFESA

now, even if malicious text comes via graceperiod/timezone, they will be
ignored
more thorough checks of parameter values
add test cases for combineDateTime

removed redundant test cases
improved function to handle exceptional cases
debugged convertToDate
missed a possible exception IFESA
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1854
minor changes in coding format/std.
Merge branch 'master' into Issue1854
[1854] Clean up InstructorFeedbackEditSaveAction

fixes #1854