lookup app summary packaged zip download links (bug 894110)

Down at the bottom of the App Summary page (eg. https://marketplace.firefox.com/lookup/app/418364/summary ) there is a Version History section with a bunch of files in it.  All the file names should be links to download the packaged apps.  All of those versions are accessible from the status & versions page (eg. https://marketplace.firefox.com/developers/app/here-maps-packaged/status ).