Allow DataSetAdapter<?> creation

There is some cases where we need flexibility on item views creation. For exemple when using libraries that require to inherit ```android.widget.BaseAdapter``` or with the ```RecyclerView``` ```ViewHolder``` approach.

So I added ability to create a ```DataSetAdapter<?>``` for a dataSet property of a presentation model.

Now we can easily create a generic, RoboBinding powered ```RecyclerView.Adapter``` (can be usefull for #184) :
 
```java
public class GenericAdapter extends RecyclerView.Adapter<GenericAdapter.ViewHolder> {

    private final DataSetAdapter<?> dataSetAdapter;

    public TasksAdapter(DataSetAdapter<?> dataSetAdapter) {
        this.dataSetAdapter = dataSetAdapter;

        dataSetAdapter.registerDataSetObserver(new DataSetObserver() {
            @Override
            public void onChanged() {
                notifyDataSetChanged();
            }
        });
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = dataSetAdapter.getView(0, null, parent);
        return new ViewHolder(v);
    }

    @Override
    public void onBindViewHolder(ViewHolder viewHolder, int position) {
        dataSetAdapter.getView(position, viewHolder.itemView, null);
    }

    @Override
    public int getItemCount() {
        return dataSetAdapter.getCount();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {

        public ViewHolder(View itemView) {
            super(itemView);
        }
    }
}
```