move download_url from topic resource to utils
save images to default_storage
generate thumbnails for all images
make sure we have an image path before stripping it
forgot to import image related exceptions
implement function removing image and thumbnails
remove old images and thumbnails on image field update
define thumbnail sizes in settings
compute files to delete from thumbnail sizes defined in settings
forgot to replace some thumbnails generation
sexify thumbnails dict comprehension
Finish rebase
Used root lambda
Removed useless import
Use public URL
Updated common
Better image support
Update URL
Used thumb name
Better error support