Release changes for 2.2.0

[jdeathe]

• Updates source image to 2.5.0.
• Updates and restructures Dockerfile.
• Updates default HEALTHCHECK interval to 1 second from 0.5.
• Updates container naming conventions and readability of Makefile.
• Fixes issue with unexpected published port in run templates when DOCKER_PORT_MAP_TCP_11211 is set to an empty string or 0.
• Adds placeholder replacement of RELEASE_VERSION docker argument to systemd service unit template.
• Adds error messages to healthcheck script and includes supervisord check.
• Adds consideration for event lag into test cases for unhealthy health_status events.
• Adds port incrementation to Makefile's run template for container names with an instance suffix.
• Adds improved memcached-wrapper script including optional Details output.
• Adds validation on MEMCACHED_CACHESIZE and MEMCACHED_MAXCONN - fails back to default if not a positive non-zero integer.
• Adds docker-compose configuration example.
• Adds improved logging output.
• Removes use of /etc/services-config paths.
• Removes X-Fleet section from etcd register template unit-file.
• Removes the unused group element from the default container name.
• Removes the node element from the default container name.
• Removes unused environment variables from Makefile and scmi configuration.
• Removes container log file /var/log/memcached.log.