2.3.1

• Deprecate Makefile target logs-delayed; replaced with logsdef.
• Updates rsyslog package to 8.24.0-41.el7_7.
• Updates source image to 2.6.1.
• Updates test/health_status helper script with for consistency.
• Updates Makefile target logs to accept [OPTIONS] (e.g make -- logs -ft).
• Updates healthcheck script; state file existence confirms bootstrap completion.
• Updates healthcheck failure messages to remove EOL character that is rendered in status response.
• Updates wrapper script; only emit "waiting on" info message if bootstrap hasn't completed.
• Updates ordering of Tags and respective Dockerfile links in README.md for readability.
• Adds improved test workflow; added test-setup target to Makefile.
• Adds Makefile target logsdef to handle deferred logs output within a target chain.
• Adds /docs directory for supplementary documentation and simplify README.
• Fixes docker-compose example configuration files to work on CentOS-7 hosts.
• Fixes validation failure of 0 second --timeout value in test/health_status.