WIP: Mongo store.ts schema

[pmespresso]

submitting a WIP pull request to start this task as I'm new to this project. Does this look along the lines what you're looking for? @shrugs

[shrugs]

good start!

basically, we'll want to implement IPersistInterface like we've done here: https://github.com/XLNT/gnarly/blob/master/packages/gnarly-core/src/stores/sequelize.ts#L103

but using mongoose instead.

We'll also want to implement a typestore, which understands how to accept json-patch patches and update the backing store correctly

https://github.com/XLNT/gnarly/blob/master/packages/gnarly-core/src/typeStore/Sequelize.ts#L28

[shrugs]

Hey @yjkimjunior I've gone ahead and closed the mongo issue, since we're going to be moving forward with #32 and adding pouchdb support. thanks for your attempt!