When you create a new instance using 'activemq create <instance-name>', but
don't begin the <instance-name> with 'activemq-instance-', then the script will create the instance anyway BUT WILL READ THE WRONG ACTIVEMQ.XML file on startup! It will read $ACTIVEMQ_HOME/conf/activemq.xml,
not $ACTIVEMQ_BASE/conf/activemq.xml.
If the intent is that all instances should be prefixed with 'activemq-instance-', then we should not allow users to accidentally create incorrect instances. Alternatively, if we are going to allow users to create instances using their own naming schemes, then we should ensure that we read the correct configuration file.