Revert "Release 319.17-0ubuntu1"

This reverts commit 33f2ad7691deb5fd72feec98d929de9735796cd9.
debian/postinst: call adduser with --system
debian/rules: call dh_installinit with --onlyscripts
debian/control: depend on adduser
Disable calls to initctl
Normalise the removal of the upstart job
debian/preinst: remove unused variable
debian/postinst: use adduser instead of useradd
Release 319.17-0ubuntu1
Revert "Release 319.17-0ubuntu1"

This reverts commit b957adb9240743a166977ca384858d8680faea9f.
debian/control: insert the correct description for the package
debian/postinst: remove line that was never used
debian/postrm: remove nvidia-persistenced user
debian/rules: add download-sources target
debian/control: bump standards
Release 331.17-0ubuntu1