fix(travis): node version

.travis.yml

@@ -1,14 +1,13 @@
 language: node_js
 node_js:
-    - "0.10"
+    - "6"
 before_install:
     - sudo apt-get install libcairo2-dev libjpeg8-dev libpango1.0-dev libgif-dev build-essential g++
     - sudo apt-get install graphviz
-    - npm install npm@1.4 -g
 install:
     - npm install -g gulp
     - npm install
-script: 
+script:
     - npm run test
 after_success:
-    - npm run coveralls
+    - npm run coveralls