[PDI-9064] Add the ability to unwind a JSON array in the MongoDB input Step.
Unit tests for MongoDbInput.
Authentication against a Mongo db now uses authenticateCommand() instead of authenticate() in order to report error information when authentication fails.
Merge pull request #87 from m-a-hall/mongoInOutImprovements

[PDI-9064] Add the ability to unwind a JSON array in the MongoDB input Step