install-script: Follow FHS rules

systemd/smartdns.service.in

@@ -0,0 +1,18 @@
+[Unit]
+Description=smart dns server
+After=network.target 
+StartLimitBurst=0
+StartLimitIntervalSec=60
+
+[Service]
+Type=forking
+PIDFile=@RUNSTATEDIR@/smartdns.pid
+EnvironmentFile=@SYSCONFDIR@/default/smartdns
+ExecStart=@SBINDIR@/smartdns -p @RUNSTATEDIR@/smartdns.pid $SMART_DNS_OPTS 
+KillMode=process
+Restart=always
+RestartSec=2
+
+[Install]
+WantedBy=multi-user.target
+Alias=smartdns.service