[model,refator][s]: reintroduce summary on Record object deprecating recordSummary on Dataset.

* Reverses change in 1dadc1106b
* Record now has fields attribute passed down from Dataset. This is needed in order to support summary method and also makes sense -- as pointed out by @zephod
* Update examples

_includes/tutorial-basics-ex-fields-2.js

@@ -6,5 +6,5 @@ dataset.fields.models[6] = new recline.Model.Field({
   type: 'geo_point'
 });
 var rec = dataset.records.at(0);
-$el.append(dataset.recordSummary(rec));
+$el.append(record.summary());