Replace system properties with command line options

[Frank Scholten]

See https://github.com/mesos/elasticsearch/tree/master/commons/src/main/java/org/apache/mesos/elasticsearch/common/cli

[James H. Fisher]

@mwl I think we can close this -- you replaced it with the Spring Boot config thingamajig which lets us use command-line options

[Martin Westergaard Lassen]

It means, replace java -Dfoo=far -jar … with java -jar … --foo=bar. Anyway. It's included in my Spring refactoring.