enforce use of environment variables when running as a service
CW_INSTANCES_DIR, CW_INSTANCES_DATA_DIR, CW_RUNTIME_DIR must be
positionned at the system level. This will ensure that cubicweb-ctl
commands issued on the computer will use the proper directories.
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