feature: add configurable system environment

running things like sysctl in a docker/lxc container doesn't work. to get around this issue and similar ones, make it configurable for OS-hardening

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
Merge pull request #3 from TelekomLabs/system-environments

feature: add configurable system environment
version bump to 0.1.1

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>