Consistent docker names

Declare consistent instance names and ports as declared in the compose file of VILLASweb's front-end

Dockerfile

-FROM node:argon
+FROM node:7-slim
 
 # Bundle app source
 COPY . .
@@ -7,5 +7,5 @@ COPY . .
 RUN npm install
 
 # Run the app
-EXPOSE 3000
+EXPOSE 4000
 CMD [ "npm", "start" ]