Build: Add Node 6.x to Travis (fixes eslint#99)

Author: dannyfritz

.travis.yml

@@ -3,5 +3,9 @@ sudo: false
 node_js:
     - "0.12"
     - 4
+    - 6
+before_script:
+    - npm install -g npm-install-peers@'1.0.1-rc.2'
+    - npm-install-peers
 after_success:
     - npm run coveralls