#1 Add a init container to do the chown job

The docker init script begins with a massive chown of all files. If you have lots of files and/or a slow IO disks, it may takes ages to start peertube, and it's sometimes useless if you have full control over your directories. EG: all files are created by Peertube and so already owned by it. This MR overload the docker init script to remove this chown, and add an init container in the kubernetes definition to do this job. And if you want, you may disable the init container to have a Peertube instance starting very quickly :muscle: