To remove the need for running privileged mode, set the necessary
`net.ipv4.conf.all.src_valid_mark=1` sysctl via docker and modify the
`/usr/bin/wg-quick` script from setting the sysctl
* Set `net.ipv4.conf.all.src_valid_mark=1` sysctl via docker `--sysctl`
* Set CAPs of NET_ADMIN and SYS_MODULE instead of using `--privileged`
* Check that `net.ipv4.conf.all.src_valid_mark=1` is set in entrypoint
script
Fixes#2