remove a few newlines

Dockerfile

@@ -1,12 +1,9 @@
 FROM node:8-onbuild AS build
-
 COPY . /app
 WORKDIR /app
-
 RUN npm install
 
 FROM node:8-alpine
 COPY --from=build /app /app
 WORKDIR /app
-
 CMD node app.js -p 3000