Merge pull request #775 from abdonrd/enabling_caching_on_travis

Enabling caching of node_modules on Travis

.travis.yml

@@ -1,5 +1,9 @@
 language: node_js
 sudo: false
+node_js:
+  - '0.12'
+  - '4.2'
+  - '5.1'
 addons:
   firefox: latest
   apt:
@@ -9,10 +13,9 @@ addons:
     packages:
       - google-chrome-stable
       - g++-4.8
-node_js:
-  - '0.12'
-  - '4.2'
-  - '5.1'
+cache:
+  directories:
+    - node_modules
 before_script:
   - 'export DISPLAY=:99.0'
   - sh -e /etc/init.d/xvfb start