fix layers in GeoModel::can_edit? not being cached per GeoModel subclass, so subclasses interfered with each other
fix layers in GeoModel::can_edit? not being cached per GeoModel subclass, so subclasses interfered with each other

mapfish-appserver/gb_mapfish_appserver,mapfish-appserver/gb_mapfish_appserver,mapfish-appserver/gb_mapfish_appserver