Merge branch 'master' into nodejs

.travis.yml

 sudo: required
 language: node_js
 node_js:
+  - "node"
   - "10"
+  - "8"
+  - "6"
 env:
   global:
     - BACKEND_CPU=true EXCLUDE_UNCOMPRESSED=true
@@ -10,6 +13,7 @@ env:
     - ENV=node
 addons:
   chrome: stable
+install: npm install
 before_install:
  - export DISPLAY=:99.0
  - sh -e /etc/init.d/xvfb start