Update Dockerfile, order installs, NODE_ENV, add entrypoint

Dockerfile

@@ -1,8 +1,13 @@
 FROM node:8.1
 
-COPY . /app
+# First install dependencies
+COPY ./package.json ./app/
 WORKDIR /app/
-ENV NODE_ENV docker
+ENV NODE_ENV production
 RUN npm install --no-progress --production && npm install --no-progress passport-ldapjs
+# Later, copy the app files. That improves development speed as buiding the Docker image will not have 
+# to download and install all the NPM dependencies every time there's a change in the source code
+COPY . /app
 EXPOSE 3000
+ENTRYPOINT ["/app/docker-entrypoint.sh"]
 CMD ["node", "index.js"]