tidy up demo collections-4

[kjdon]

Once ticket #381 has been completed, delete the images from the documentsed example collections. - remove image files and edit collect.cfg.

Do we want to do this before or after #380 (putting the colls into svn). If we do this first, we can still retrieve the images from old releases, and then don't clutter up the repository with images that we never use again.

[kjdon]

Collection images all gone