Update mongo driver to 3.7 LTS

[aellert]

Is your feature request related to a problem? Please describe.

Mongo driver is quite old, I have some stability issue on recent MongoDB server version. Also some option were renamed and it's very confusing. For exemple, secondaryAcceptableLatencyMS renamed to localThresholdMS.

Describe the solution you'd like

Upgrade to mongo 3.7 LTS (https://www.npmjs.com/package/mongodb/v/3.7.3)

Describe alternatives you've considered

Actually I build a custom Docker image with modified package.json and updated mongo driver.

[aellert]

Please also include persona-service at least 1.8.0 (https://github.com/LearningLocker/persona-service/releases/tag/v1.8.0) which include Mongo 3 Node.js Driver