Add a GravityView data source

[zackkatz]

It would be great to render a GravityView View using a Table layout in DataKit.

• Parse the View configuration and use that for field types, order, etc.
• Support the field settings (at least custom label to start)
• Defer to View settings for pagination, sorting, etc

The only thing that would need to configure a DataView using DataKit + GravityView would be a View ID. Pretty epic.