Remove unzipped disk image before unzipping. This ensures that the disk image is up to date.
Remove unzipped disk image before unzipping. This ensures that the disk image is up to date.

git-svn-id: 765db44a9620ed55f4f8addfd3c14fe8cd57f6bb@2832 0fceea05-a30d-0410-8a8b-80ef821fb0a1

nanoant/Skim,nanoant/Skim,nanoant/Skim,nanoant/Skim,nanoant/Skim