debian: ship systemd service file

debian/ai-sso-server.service

+[Unit]
+Description=AI SSO Server
+After=network.target
+
+[Service]
+PIDFile=/var/run/sso/sso_server.pid
+User=ai-sso
+Group=ai-sso
+WorkingDirectory=/var/run/sso
+Environment=SSO_PORT=5002
+ExecStart=/usr/bin/gunicorn \
+    --log-config=/etc/sso/logging.conf \
+    --bind 0.0.0.0:${SSO_PORT} \
+    --worker-class gevent \
+    --pid /var/run/sso/sso_server.pid \
+    --name ai-sso-server \
+    sso_server.wsgi:app
+ExecReload=/bin/kill -s HUP $MAINPID
+ExecStop=/bin/kill -s TERM $MAINPID
+PrivateTmp=true
+Restart=on-failure
+
+[Install]
+WantedBy=multi-user.target