tweak package file

package.json

@@ -7,6 +7,6 @@
   "devDependencies": {
     "gulp": "^3.9.1",
     "laravel-elixir": "^5.0.0",
-    "bootstrap-sass": "^3.3.0"
+    "bootstrap-sass": "3.3.6"
   }
 }