Merge pull request #326 from mozilla/node-10 r=@vladikoff

feat(docker): Use node 10 to build the docker image

.travis.yml

@@ -5,8 +5,7 @@ env:
   global:
     - TMPDIR=/tmp
 
-node_js:
+node_js: "10"
- - '8'
 
 sudo: false
 

Dockerfile-build

@@ -1,4 +1,4 @@
-FROM node:8-alpine
+FROM node:10-alpine
 
 RUN npm install -g npm@6 && rm -rf ~app/.npm /tmp/*
 
@@ -13,6 +13,6 @@ USER app
 COPY npm-shrinkwrap.json npm-shrinkwrap.json
 COPY package.json package.json
 
-RUN npm install --production && rm -rf ~app/.npm /tmp/*
+RUN npm ci --production && rm -rf ~app/.npm /tmp/*
 
 COPY . /app