Add new Docker concept

[piotrkardasz]

The new concept allows to setup environment with just one command 🚀

make init # initialize Sylius installation with required dependencies

ENV=test make run # to change the environment to test

make debug # to run php container with xDebug + mailhog

Requirements

• Docker
• Makefile

used dependencies

• https://github.com/sylius/docker-images - ready to use Sylius images
• https://github.com/boxboat/fixuid - fixes user ID between local machine and docker container (required for Linux)