Kits: Do not trigger unmanagedKitUpdated signals during construction

Stay below the radar during construction/fromMap. This avoids some
signals from the KitManager about unmanaged kits having been updated.

This signal is used in three places only and always connected only
after the the construction happend. So this should be safe.

Change-Id: If6cc29b6bb98fa161776a9a79f48f88173db04b8
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>