1. remove "no reply" from sender name and sender email
2. fix related tests
move emphasis from date/time to timeTaken
Moved BackDoorTest and GodModeTest out of staging tests.
Merge branch 'master' of https://github.com/TEAMMATES/repo
1. add background colour for table cell
change magic numbers into constant
Merge pull request #2268 from TEAMMATES/Issue2261

adminActivityLog: de-emphasize date/time, emphasize time taken #2261
Merge pull request #2267 from TEAMMATES/Issue2262

remove 'no reply' from TEAMMATES emails #2262
add course delete cascade logic test
instructors delete cascade test
studentLogic test
Merge branch 'dev' into 74590202

Conflicts:
	src/main/java/teammates/logic/core/StudentsLogic.java
Merge branch 'master' into 74590202
dev green
Merge branch '74590202' into dev