Mongoose Document Versioner

This module sets a document version key that is incremented
any time you save or update a document. This is useful for
detecting version conflicts.

Increments version on the following pre hooks:

* findOneAndUpdate
* updateOne
* updateMany
* update
* save

Note: Model.findByIdAndUpdate() calls the findOneAndUpdate hook.

Usage

``js
const versionerPlugin = require('mongoose-document-versioner');

const schema = new mongoose.Schema({ / .... / });
schema.plugin(versionerPlugin);
const Model = mongoose.model('Model', schema);

/ EXAMPLES /

Model.update({attr: 'foo'}, {attr: 'bar'}, {multi: true});
/*
* mongo query:
* model.update(
* { attr: 'foo' },
* { '$inc': { version: 1 }, '$set': { attr: 'bar' } },
* { multi: true }
* )
*/

Model.findOneAndUpdate({attr: 'foo'}, {attr: 'bar'});
/*
* mongo query:
* model.findAndModify(
* { attr: 'foo' },
* { '$inc': { version: 1 }, '$set': { attr: 'bar' } },
* { new: false, upsert: false }
* )
*/
``