This change involves using non-root user to run the process of the
docker images. Also made update in Dockerfile to make the containers
support "read-only" and introduce "HEALTHCHECK". Note the "read-only"
options are not enabled in docker-compose, to cover the very corner
case when user wants to update the container filesystem manually.
Remove read only option from docker-compose template by default
This change mitigate problems with container restarts (stop, start) or automatic restart after host machine restart. Rsyslogd strictly checks existence of its pid file and won't start if such one exists.
