Adds vistrails.tests.__main__
Adds vistrails.tests.__main__

This allows using "python -m vistrails.tests" to run the unit tests.

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