Fix EAS sending, which was inadvertently broken by a change in EmailProvider

* syncServerId in the Message table can now be NULL; this broke a test
  used by EasOutboxService and SyncManager to determine whether there
  were sendable messages in the Outbox
* Changed test to allow for NULL in syncServerId

Change-Id: Id76c7a45bc306abe7a927ab2395700f54a01a298
1 file changed