Sort Message Center on server message creation time rather than client creation time.
Testing for IOS-589
Add comments in places where server `creationTime` overwrites `clientCreationTime`.
Method `updateClientCreationTime` shouldn't set server `creationTime` unless `creationTime` is empty.
IOS-589
Merge branch 'MessageCenterOrder' into creationTime
Removed `Survey` and `Ratings` sections from FeedbackDemo, added `Events`.
Fixes IOS-484 and IOS-274
Clean up Feedback Demo
Fixes IOS-484 and IOS-274