changed docker file nest to avoid rebuild everything each time, and small changes in chat gateway

tests_hugo/chat_node/README.md

@@ -0,0 +1,54 @@
+
+- [socket io multi room chat](http://psitsmike.com/2011/10/node-js-and-socket-io-multiroom-chat-tutorial/)
+
+first time :
+	npm install --save express socket.io cors
+	sudo npm install -g nodemon
+
+next time :
+	npm install
+
+anytime :
+	nodemon server
+
+- [ ] don't send message to oneself
+- [ ] create a room
+- [ ] automatically add someone to a room
+- [ ] being able to accept or refuse to be added to a room
+- [ ] what to do with message not received ?
+
+```
+-> create_public_conv( room_name );
+-> create_private_conv( room_name );
+->   create_protected_conv( room_name );
+-> create_direct_conv( room_name );
+
+-> change_conv( room_name );
+
+-> get_conv_history( room_name );
+-> get_last_conv();
+
+-> get_my_convs_directs( );
+-> get_my_convs_rooms( );
+-> get_public_convs( );
+
+[ list     ][ create   ][ join     ]
+  "directs"   . [direct]  (public and protected)
+  "rooms"     . [room]
+                . public
+                . private
+                . protected
+
+on connection :
+	get_convs_directs();
+	get_convs_rooms();
+	last_conv = get_last_conv();
+	if (last_conv)
+		get_conv_history(last_conv);
+
+
+```
+## todo:
+- check if drop down menu works also with buttons instead of <div tabindex=0>
+- add window for option when select 'room'
+