A whitelist for dynamic reconfigure

For when you don't want to have to show or crawl through all the parameter noise. A simple whitelist might look like:

```
    whitelist = {
         'Beachhead': ['show_incoming_pose_updates'],
         'Image Control Handle': ['value'],
         'Image Source': [
             'show_image_pair_timestamps',
             'show_stereo_parameters',
         ],
    }
```