challenge registration api fix

requirements:

1. add timeline notification for dev, too.
	add the code logic, also add its related test case.

2. check the notification is set.
	
	This is fixed by adding an "else" block to method timelineNotification() in challengeRegistration.js

3. add a test to verify register the design challenge twice should fail.
	done.

4. validateDatabaseForDevelop() is only designed for project 40000001, so it should not be used in it('User register a copilot posting challenge') in test.challengeRegistration.js