CI: change npm install to yarn

JPeer264 · JPeer264 · commit 6c245c0aeb12 · 2017-05-06T22:46:25.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -5,8 +5,7 @@ node_js:
   - "4"
   - "6"
 install:
-  - npm i -g npm
-  - npm install
+  - yarn
 script: npm test
 notifications:
   email:
