IMAGE_SIZES can now be overridden using LFC_IMAGE_SIZES;

Kai,

That's the change I proposed at LFC Google groups:
https://groups.google.com/forum/#!topic/django-lfc/-cPtwic2NaQ

This change allows user to override default image sizes using LFC_IMAGE_SIZES in project settings.
That might be useful when using custom sizes, also allows saving some disk space.

Thanks,
Vitaly