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 reworked the vmware/harbor-db image to build it on top of
vmware/mariadb-photon.
Also made minor change in the entrypoint script of mariadb image to
execute upgrade script during bootstrap, and fix a file permission
issue in the bootstrap scripts.
