Fix travis phantomjs bug and add build cache

.travis.yml

@@ -1,11 +1,15 @@
 language: node_js
 node_js:
-- '0.8'
+- '4.4'
+
+cache:
+  directories:
+  - node_modules
+
 before_install:
-- npm install -g npm
 - npm install -g grunt-cli
+
 deploy:
   provider: npm
   email: [email protected]
-  api_key:
-    secure: dRbQr9FJxULs1vE3TVSWRSUSuBAeH9emy2s+8hweEZdpNLJaiUWIDFHGe754CiPZlL70vXKTVp+gHLIGViRTevE77LH2VHkrjZDItQNIRR7KiD6x2QuZ8iFgEojC+VQvIvGjqnP8uoeA6RHfONDxQiBD9/kRaBs8v6WArsqenTA=
+  api_key: $NPM_TOKEN