set correct options from mongo uri parsed by pymongo

[jbouzekri]

https://github.com/mongodb/mongo-python-driver/blob/master/pymongo/common.py#L465

Based on this mapping, we can see that pymongo lowercase the keyword and is not adding underscore

[dcrosta]

Hi @jbouzekri

Thanks for contributing this, and apologies for not having gotten back to you in so long. Ultimately, I don't think I'm going to merge this, because I suspect it would cause compatibility issues with PyMongo 2.x which current versions of Flask-PyMongo support.

Instead, I'm going to being working on Flask-PyMongo 2.0 which will drop support for all of the individual settings, and instead just take a URI -- that way it will support whatever options your version of PyMongo itself supports.

[dcrosta]

Ah, sorry, please ignore my last comment -- I thought this was talking about keyword arguments to the MongoClient not values from the connection string. Appreciate the contribution.