Cgiv 3688 ekm import listings gmf

Some of the code may look 'odd' compared to our usual standards, e.g. a public variable, however I've done this to retain the original authors codeflow as they mix JS and php through the public variables so it's hard to get rid of them without a re-design
Make this more generic, e.g. `getDownloadLocation` rather than `getZipDownload`