Default to request server id if MoveItems response lacks one.

The documentation says it's a required element of the response
but dogfooder reports a crash implying otherwise.

http://msdn.microsoft.com/en-us/library/gg663427(v=exchg.80).aspx

Bug: 11186535
Change-Id: I10f64de7ccc4c6293ace40dcd6e3c4ce3eda80ab
1 file changed