Remove/Fix deprecation warnings

[SmithPeder]

When createing users using CLI

• (node:53354) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.

• (node:53354) DeprecationWarning: collection.ensureIndex is deprecated. Use createIndexes instead.

When running tests

• (node:53380) [DEP0097] DeprecationWarning: Using a domain property in MakeCallback is deprecated. Use the async_context variant of MakeCallback or the AsyncResource class instead.