Added another Bushing mobilizer test.
Added another Bushing mobilizer test.

chrisdembia/simbody,robojukie/simbody,scamille/simbody,Gjacquenot/simbody,scamille/simbody,Gjacquenot/simbody,elkingtonmcb/simbody,elkingtonmcb/simbody,robojukie/simbody,Gjacquenot/simbody,scamille/simbody,elen4/simbody,chrisdembia/simbody,chrisdembia/simbody,robojukie/simbody,elen4/simbody,simbody/simbody,simbody/simbody,elkingtonmcb/simbody