Revert "Revert "marking for later reference""

This reverts commit 05810baf9701460fa6da46fd55cbd865ba656eea.
Revert "marking for later reference"

This reverts commit 15281f0b3fb0518be75885fa2ce8eb00eb5d4a6e.
Changed the parameters of feedback sessions from simply the typical values to increase coverage
Changed an existing test case to expand coverage. Debugged a malfunctioning method
changed and added a few test cases

used assertion instead of exception
added timezone tests
Merge remote-tracking branch 'origin/master' into Issue1816
added test cases for session name and timezone
test cases for FSA

changed a function in FSA that took an int for timezone instead of
double
better coverage and removed front-end validation

the js code is still available, but the validation call is not made.
added enums for values related to dates

Session Visible Time
Results Visible Time
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1816
added db inconsistency message to user

Added a const for the message
Refactored code to organise the conditions
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1816
lsat few tweaks- added a TODO and changed a few comments
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1816
Merge branch 'master' into Issue1816
[1816] Clean up InstructorFeedbackAddAction

fixes #1816