systemd: Add a service unit for ynh-vpnclient

conf/ynh-vpnclient.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=YunoHost VPN Client.
+Requires=network.target
+After=network.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/local/bin/ynh-vpnclient start
+ExecRestart=/usr/local/bin/ynh-vpnclient restart
+ExecStop=/usr/local/bin/ynh-vpnclient stop
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target
+Alias=ynh-vpnclient.service