Pip install copies CHANGES,rst, LICENSE, README.rst to /usr

[wdoekes]

The following files should be in a different location:

  /srv/virtualenvs/planb/CHANGES.rst
  /srv/virtualenvs/planb/LICENSE
  /srv/virtualenvs/planb/README.rst
^-- +share/doc/planb/
...
  /srv/virtualenvs/planb/planb-queue.service
  /srv/virtualenvs/planb/wsgi.py
^-- +share/planb/ ?

We could then use ${VIRTUAL_ENV:-/usr}/share/planb/ as the source path for copying the planb-queue.service.