Create an @joystick.js/mongodb @joystick.js/postgresql packages and standardize driver connections

[rglover]

This just came up in relation to the testing portion of Joystick. Both the app framework and the test framework need access to databases in the exact same way. I'm going to temporarily just copy/paste what I have in Node, but this should be consolidated in a package so there are no hiccups adding new databases/drivers later.

[rglover]

This also plays nicely with being able to customize a new app build via the CLI. Can just do a select list and install the appropriate drivers dynamically vs. just having the kitchen sink.