Fix cascading modes
Fix cascading modes

Need to check __dict__ for attributes, otherwise we'll match
superclass's attributes too.  Need to update the compute method to
work with cascading, too.

hjanime/VisTrails,VisTrails/VisTrails,minesense/VisTrails,minesense/VisTrails,VisTrails/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,Nikea/VisTrails,Nikea/VisTrails,hjanime/VisTrails,minesense/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,hjanime/VisTrails,minesense/VisTrails,Nikea/VisTrails,minesense/VisTrails,celiafish/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,celiafish/VisTrails,hjanime/VisTrails