Allow specifiying mongodb find options

[Timeraa]

When the DataLoader runs the mongodb query it should allow the user to specify some options like projection as you don't need to cache/fetch fields that you don't use in your queries.

[lolo-io]

I agree. Unfortunately the lack of options makes this datasource implementation too limited for my app.

[Timeraa]

If it helps, I made my own adaption of it here, it includes projection as it's features as well as we highly depend on it.