VCS: Invert Command -> runVcs dependency

* Unclutter runVcs
* Enable more dynamic signal/slot usage in Command

Change-Id: Ie97b17078778b0c86b74d5725a78e766828ac6d8
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>