update npm package versions

Author: butschster

package.json

@@ -4,8 +4,9 @@
     "gulp": "^3.8.8"
   },
   "dependencies": {
-    "laravel-elixir": "^4.0.0",
-    "bootstrap-sass": "^3.0.0",
+    "gulp": "^3.9.1",
+    "laravel-elixir": "^5.0.0",
+    "bootstrap-sass": "^3.3.0",
     "bower-installer": "^1.2.0"
   }
 }