[#425] Fix Dataset.query() when called with Query model

The problem is that Backbone >= 0.9.9 doesn't accept updating models with:

    model.set(otherModel);

That needs to be changed to:

    model.set(otherModel.attributes);

Dataset.query() accepts both regular JS objects and Query models, so we need to
check the parameter type to support both.

src/model.js

@@ -191,7 +191,11 @@ my.Dataset = Backbone.Model.extend({
     this.trigger('query:start');
 
     if (queryObj) {
-      this.queryState.set(queryObj, {silent: true});
+      var attributes = queryObj;
+      if (queryObj instanceof my.Query) {
+        attributes = queryObj.toJSON();
+      }
+      this.queryState.set(attributes, {silent: true});
     }
     var actualQuery = this.queryState.toJSON();