chore(package): update webpack to version 1.13.0

http://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -11,7 +11,7 @@
   },
   "devDependencies": {
     "gulp": "~3.9.0",
-    "webpack": "~1.12.11",
+    "webpack": "~1.13.0",
     "gulp-webpack": "~1.5.0",
     "gulp-rename": "~1.2.0",
     "gulp-uglify": "~1.5.1",