Robert Maynard authored Sep 26, 2014 and Brad King committed Nov 13, 2015

While the DragNDropGenerator supports custom DS_Store and backgrounds,
it is still very hard to automatically setup nice looking packages. The
primary issue is that the DS_Store embeds the name of the volume in the
path to backgrounds, which means that if a package embeds the version in
its volume name a new DS_Store must generated for each release.

Instead one now can use applescript to setup the DS_Store.

This change also ensures that temporary RW image has enough space for
these changes, creating 1 MB dummy padding file, that is later removed
from the image.

Co-Author: Adam Strzelecki <adam.strzelecki@java.pl>