add custom option to hoodie.store method calls

so they can be distinguished from method calls coming from outside.

What I want is to do this:

```js
var Collection = BaseCollection.extend({
  model: Model,

  initialize: function() {
    var type = this.model.prototype.type;
    Backbone.hoodie.store.on('change:'+type, _.bind(this.handleMeetingChange, this));
  },

  handleMeetingChange: function(eventType, object, options) {
    if (options.backbone) return;
    // update collection here
  }
});

makes sense?