chore(ci): build docker image

Author: bufferoverflow

.travis.yml

@@ -1,4 +1,6 @@
 language: node_js
+services:
+  - docker
 sudo: false
 node_js:
   - 'lts/carbon'
@@ -10,3 +12,4 @@ script:
   - yarn lint
   - yarn code:build
   - yarn test:all
+  - yarn build:docker