Including Panopoly and allowing Drupal.org packaging of the distribution.

This is how Open Atrium/HotSauce!/others include other distributions in their build (as well as create a build that can be automatically packaged by Drupal.org and built with one command by others).

Don't know if you're still interested in including Panopoly, but this model is probably more recognizable to folks and gives an easy one-line build.

Note that if you try to test this, you'll want to change the git URL to my Github fork (https://github.com/johnstorey/hap).