[devtools] make a copy of the xvfb-run script so we can kill it properly
Since changeset a3d3bdd46463 we don't run firefox directly but through a
wrapper script. This meant that on stopping the test, we would kill
that wrapper script but leave the Xvfb server and firefox processes
running. So make a local copy of xvfb-run, and make it kill Xvfb when
it goes down, not just when its client exits.
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/web usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/share/cubicweb/cubes/shared/data usr/share/cubicweb/cubes/shared
debian/tmp/usr/share/cubicweb/cubes/shared/wdoc usr/share/cubicweb/cubes/shared