UID/GID environment variables

[cgrima]

Allow the user to set the UID/GID for the i-librarian user. Would avoid to have to manually set them to 33:33 on the library folder.

[alfureu]

Hi @cgrima could you please provide this ENV option?

[cgrima]

That would be a great upgrade but, unfortunately, don't have much time now. Any contribution would be welcome.