Add new attributes for entity
Add append and delete respondant function for session
Add append and remove function in feedback submission save action
Add delete respondants function when deleting instructor or student
Change logic in retrieving response rate
Merge branch 'master' into Issue2452
Fix showing unresponding participants and add function to be used in restoring data bundle
Merge branch 'master' into Issue2452
Add handle when deleting questions and migrating script
Initialize datastore
Fix test cases
Refactor code and enhance migrate script
Merge branch 'master' into Issue2452
Change storing the list of respondants by emails
Fix bugs
Merge branch 'master' into Issue2452
Fix test
Refactor code
Merge branch 'master' into Issue2452
[2452] Change logic in getting response rate