pushed mongodb native package to v3.0

[Freundschaft]

hey there,

I updated the package to use mongodb native 3.0, so sails users can make use of the new mongodb 3.6 version. I choose to not completely rewrite everything so that it matches the new mongoclient logic, but instead attached the mongoclient object to the manager as the client attribute so it can be accessed.

for the changes introduced in mongodb native driver 3.0 see https://github.com/mongodb/node-mongodb-native/blob/3.0.0/CHANGES_3.0.0.md

Please review and merge if suitable

[gil0mendes]

This change is really interesting to support the more recent protocol mongodb+srv. Now that mLab is going away MongoDB Atlas uses a replica set even for the free server.

[DominusKelvin]

Hey @Freundschaft and @gil0mendes, I'll be closing this PR as this other PR has implemented the upgrade and it has been merged. Thank you for working on this @Freundschaft 💙

Also you can check here for the upgrade information. 👇🏾

https://blog.sailscasts.com/sails-mongo-v2-1-0