[SyncEvolution] Keepalives when syncing

Well, it turns out that to prevent the Jolla from suspending itself in the middle of a sync (or more likely, data backup or data diff), I should send some D-Bus message to the MCE daemon at the start of a sync, and then keep sending it regularly until the sync is done, at which point I should send a final message. Here's the interface: https://github.com/nemomobile/mce-dev/blob/master/include/mce/dbus-names.... Now where in the SyncEvolution code would it be wise to hook in to do something like that?