b/17443087
When we migrate exchange accounts, we copy mailboxes over to the
new account (in order to preserve sync frequency and window).
The problem with this is, you may have many accounts/mailboxes.
After starting the app, it may take quite a long time before all
mailboxes are synced. If the user visits some mailbox near the
bottom, they'll see a misleading "folder is empty" view.
Now, when migrating, we'll set the uisyncstatus to INITIAL_SYNC_NEEDED.
Here I needed to add INITAL_SYNC_NEEDED to the list of states
that EmailConversationCursor will consider incompletely loaded.
Change-Id: Idef13adf9d691c03665830a2f926b1806d7591da
3c2f782c35