app_key should be respected from environment

[dot-mike]

If the user passes APP_KEY as part of environment variable it should be respected and used, not generating a new one.

docker/rootfs/etc/cont-init.d/04-svc-main.sh

Line 45 in 1d7c972

APP_KEY=$(artisan key:generate --no-interaction --force --show)

The reason for this is because I want to run another instance on another host for redundancy. I should be able to include the key as part of the environment variable so when it starts it will re-use the key.