Setcap causes problems (like issue #1007), so stop using it (and undo
the permission override on upgrade) and instead set capabilities via the
systemd services.
(This also fixes some AssertFileNotEmpty declarations that were in the
wrong places).
lokinet now installs just the binaries; lokinet-client and
lokinet-router install client/router configuration and services
(lokinet-client.service, lokinet-router.service), respectively.
