Merge pull request cerebral#52 from cerebral/docs1

chore(travis): use npm ci

Author: christianalfoni

.travis.yml

@@ -1,9 +1,11 @@
 sudo: false
 language: node_js
 node_js: '8'
+install:
+- npm ci
 cache:
   directories:
-  - node_modules
+  - "$HOME/.npm"
 addons:
   apt:
     sources: