Add systemd service unit for master.

This assumes an existing user called buildbot and the master config located in /srv/buildbot/master.

Signed-off-by: David Gstir <david@nod.at>
Add systemd unit for slave.

This assumes an existing user buildslave and the slave config located in /srv/buildslave/linux-slave.

Signed-off-by: David Gstir <david@nod.at>
Merge sigma-star/buildbot:systemd-units (PR #1059)