loadFactories(factoryMap = {}) {
    // Store a reference to the factories
    let currentFactoryMap = this._factoryMap || {};
    this._factoryMap = assign(currentFactoryMap, factoryMap);

    // Create a collection for each factory
    Object.keys(factoryMap).forEach((type) => {
      let collectionName = this.schema.toCollectionName(type);
      this.db.createCollection(collectionName);
    });
  }
Load factories into Mirage's database.

@method loadFactories
@param {Object} factoryMap
@public
@hide