Allow cropping images
Allow cropping images

Currently, we use Image.thumbnail for resizing images. That
resizes an image so that it is *at most* the given size.

This commit changes that so that images are first resized to
be *at least* the given size. After that they are centered and
then cropped.

alkadis/vcv,phihag/adhocracy,DanielNeugebauer/adhocracy,alkadis/vcv,alkadis/vcv,liqd/adhocracy,DanielNeugebauer/adhocracy,phihag/adhocracy,liqd/adhocracy,DanielNeugebauer/adhocracy,phihag/adhocracy,phihag/adhocracy,liqd/adhocracy,DanielNeugebauer/adhocracy,liqd/adhocracy,phihag/adhocracy,alkadis/vcv,alkadis/vcv,DanielNeugebauer/adhocracy