Build: Temporarily update gulp version for Travis tests

Author: phated

.travis.yml

@@ -1,9 +1,12 @@
 sudo: false
 language: node_js
 node_js:
-  - "iojs"
+  - "stable"
+  - "4"
   - "0.12"
   - "0.10"
+before_script:
+  - sed -i 's/4.0.0-alpha.1/4.0.0/g' node_modules/gulp/package.json
 after_script:
   - npm run coveralls
   - npm run lint