Change Travis settings

Author: ryanashcraft

.travis.yml

@@ -1,9 +1,12 @@
 language: node_js
 node_js:
-      - "5"
-      - "6"
-      - "7"
-cache: yarn
+      - "node"
+cache:
+      yarn: true
+      directories:
+            - node_modules
+            - examples/async/node_modules
+            - site/node_modules
 script:
       - yarn install --cwd examples/async
       - yarn install --cwd site