Added fail if jitsi isn't installed on start

bin/start

@@ -120,6 +120,8 @@ startservice_all_new() {
 SERVICE=$1
 
 if [ "$SERVICE" = "jitsi" ]; then
+  [ ! -d "/federated/apps/jitsi" ] && failts "* jitsi is not installed."
+
   # If jitsi is already running then skip
   [ "$(docker container inspect -f '{{.State.Status}}' jitsi-web-1 2>/dev/null)" = "running" ] && echo "* $SERVICE is already running." && exit 2
   startservice_jitsi