Bug #721286 - IMAPx: read messages become unread when reopening Evolution ][

Found one more issue when testing the same change for gnome-3-10:

d) do not use CamelOperation in the parser thread, because it can be
   cancelled at an application end with camel_operation_cancel_all() call,
   which is done too early, before any pending jobs are properly finished
   (it can be IDLE job, or save of folder changes back to the server)