Uses the new gulp version

You will need to replace your local cli too:
```
npm uninstall gulp
npm install -g gulpjs/gulp-cli#4.0
```

Author: lejoe

package.json

@@ -11,7 +11,7 @@
     "bower": "^1.3.12",
     "browser-sync": "^2.6.5",
     "del": "^1.1.1",
-    "gulp": "^3.8.11",
+    "gulp": "git://github.com/gulpjs/gulp.git#4.0",
     "gulp-a11y": "^0.1.1",
     "gulp-accessibility": "^1.2.1",
     "gulp-autoprefixer": "^2.2.0",