Added another test for 6DOF constraint.
Added another test for 6DOF constraint.

daviddeng/azrael,daviddeng/azrael,olitheolix/azrael,olitheolix/azrael,olitheolix/azrael,daviddeng/azrael,daviddeng/azrael,olitheolix/azrael,olitheolix/azrael,daviddeng/azrael