Update .travis.yml
Update .travis.yml

Run the unit tests only if "BUILD_CORE_ONLY" option is OFF
dartsim/dart,dartsim/dart,dartsim/dart,axeisghost/DART6motionBlur,dartsim/dart,axeisghost/DART6motionBlur,dartsim/dart,axeisghost/DART6motionBlur