fix(travis): Use node 6.3.1

Author: ArnaudSpanneut

.travis.yml

@@ -1,8 +1,8 @@
 language: node_js
 node_js:
-  - '0.12'
+  - '6.3.1'
 before_script:
   - 'npm install'
   - 'bower install'
 script: npm test
-after_script: "npm install coveralls@2.10.0 && cat ./coverage/*/lcov.info | coveralls"
+after_script: "npm install coveralls@2.10.0 && cat ./coverage/*/lcov.info | coveralls"