fix(package): update bufferutil to version 4.0.1

Closes #321

Author: greenkeeper[bot]

package.json

@@ -49,7 +49,7 @@
     "angular2-meteor-tests-polyfills": "0.0.2",
     "babel-runtime": "^6.23.0",
     "bcrypt": "^1.0.2",
-    "bufferutil": "^3.0.2",
+    "bufferutil": "^4.0.1",
     "dockerode": "^2.5.1",
     "file-saver": "^1.3.3",
     "lodash": "^4.17.4",