Thumbnails for Resources which are images

It would be a nice feature if the 'icon' beside a resource in a dataset could be changed by the uploader to a thumbnail. I am thinking in particular if the resource is an image, then the 'icon' would be very useful if it was a thumbnail of the image. This could also be an automated option, whereby when uploading an image resource there is an option (tick-box) to choose for CKAN to automatically make a scaled down copy of the image and use it as that resources 'icon', OR alternately to manually upload/link to an image to use (within dimension limits...). The later could be useful if automatically scaling of a particular image resulted in a not very good quality thumbnail, so the user could manually make a thumbnail that was useful.

No files, tests, or entry points are named. Start by reviewing how resource icons are displayed and how image resources are uploaded, then resolve whether automatic scaling, manual thumbnails, or both are required; done means an uploaded image can show an appropriate thumbnail within defined dimension limits.

Written by the indexing model from the issue text.