Dockerfiles update

[LudwigEnglbrecht]

Hi,
the Dockerfiles of polymorph have been updated since the used image is no longer available via docker-hub:

Please note, kalilinux/kali-linux-docker is the former official image, it’s no longer updated. Don’t use it. source

Please find attached the updated Dockerfiles with the new base image and the necessary adjustment for using python-netfilterqueue.

Dear @shramos, please check if could be useful :-)