fixed bin/build_test.sh script bug around xvfb pidfile
fixed bin/build_test.sh script bug around xvfb pidfile

ojacobson/dryad-repo,rnathanday/dryad-repo,ojacobson/dryad-repo,rnathanday/dryad-repo,ojacobson/dryad-repo,rnathanday/dryad-repo,ojacobson/dryad-repo,rnathanday/dryad-repo,jimallman/dryad-repo,ojacobson/dryad-repo,ojacobson/dryad-repo,jimallman/dryad-repo,rnathanday/dryad-repo,jimallman/dryad-repo,jimallman/dryad-repo,jimallman/dryad-repo,rnathanday/dryad-repo,jimallman/dryad-repo