hashing support

[pschrammel]

I need some help here to have hashing configurable

[guilhermef]

Hi @pschrammel, what's the use case for hashing in the storage?

[pschrammel]

It is a feature of TC_AWS that we were using for several reasons:

• we use full urls (with https:// ....) to load the original image and that was leading to very strange s3 keys
• we don't want to have our url structure visible in s3

I switched from sha1 (original in TC_AWS) to sha256 as sha1 is regarded unsafe by our security scanners though in this case it wouldn't matter

[pschrammel]

@guilhermef , I changed the concept, getting my very specific hashing is hard to get upstream. The idea now is that you can define a lambda expression that does your personal normalization magic. I hope this approach is more generic and easier to accept.