Merge pull request #650 from syuilo/greenkeeper/@types/mongodb-2.2.8

Update @types/mongodb to the latest version 🚀

package.json

@@ -47,7 +47,7 @@
     "@types/is-url": "1.2.28",
     "@types/js-yaml": "3.9.0",
     "@types/mocha": "2.2.41",
-    "@types/mongodb": "2.2.7",
+    "@types/mongodb": "2.2.8",
     "@types/monk": "1.0.5",
     "@types/morgan": "1.7.32",
     "@types/ms": "0.7.29",