Original File download 12136

Fixes https://trac.openmicroscopy.org.uk/ome/ticket/12137

To test, select an image & go to the download arrow in the toolbar in the right-hand panel. Check that "Archived File(s)" is one of the download options and that it works! Should get a zip if the download is more than one file (E.g. Leica LIF stack or Deltavision + log etc).