Bug 1057726 - Remove jetty.xml from ActiveMQ configuration
<install> Remove the jetty and jetty realm configuration

- Add comment to tell users that they should enable authentication and
  set passwords if enabling jetty.xml
Merge pull request #296 from detiber/1.2-activemq-5.9.0

<install> Changes for activemq-5.9.0 update - enterprise 1.2