Update Dockerfile

Dockerfile

-FROM node:9.5.0-stretch
+FROM node:dubnium-stretch
 
-RUN apt-get -y update -qq && apt-get install -y -qq apt-utils
+RUN apt-get -y update && apt-get install -y apt-utils
 
-RUN npm install --global gulp gulp-cli babel babel-cli babel-core babel-register mocha gulp-mocha gulp-eslint istanbul
+RUN npm install --global gulp gulp-cli babel babel-cli babel-core babel-register mocha gulp-mocha gulp-eslint istanbul --force
 
 RUN mkdir API
 
@@ -12,6 +12,10 @@ WORKDIR ./API
 
 RUN npm install
 
+RUN npm un -g gulp
+
+RUN npm i -g gulp@3.9.0
+
 RUN gulp build
 
 EXPOSE 4000