Bump mongodb from 2.2.36 to 3.1.13

Bumps [mongodb](https://github.com/mongodb/node-mongodb-native) from 2.2.36 to 3.1.13.
- [Release notes](https://github.com/mongodb/node-mongodb-native/releases)
- [Changelog](https://github.com/mongodb/node-mongodb-native/blob/master/CHANGES_3.0.0.md)
- [Commits](mongodb/node-mongodb-native@v2.2.36...v3.1.13)

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package.json

@@ -38,7 +38,7 @@
     "jquery": "^3.2.1",
     "lodash": "^4.17.10",
     "moment": "^2.19.1",
-    "mongodb": "^2.2.20",
+    "mongodb": "^3.1.13",
     "natives": "^1.1.6",
     "node-gettext": "^2.0.0",
     "request": "^2.88.0",