BUGFIX Make sure SiteID is re-written when site tree is reorganised.
BUGFIX Make sure SiteID is re-written when site tree is reorganised.

silverstripe-australia/silverstripe-multisites,xini/silverstripe-multisites,stephenmcm/silverstripe-multisites,Zauberfisch/silverstripe-multisites,xini/silverstripe-multisites,silverstripe-australia/silverstripe-multisites,Zauberfisch/silverstripe-multisites,stephenmcm/silverstripe-multisites