TEZ-1774. AppLaunched event for Timeline does not have start time set. (hitesh)

(cherry picked from commit f152a7f3bcca82a343b759c2921dbc8d93aaf175)

Conflicts:
	CHANGES.txt
Update CHANGES.txt for TEZ-1774. (hitesh)

(cherry picked from commit f4c2112f647ce1aa7b7ab9febad2118bd9451cc6)

Conflicts:
	CHANGES.txt