QPID-4390: Improve the configuration handling of command line options

git-svn-id: https://svn.apache.org/repos/asf/qpid/branches/java-broker-config-qpid-4390@1429738 13f79535-47bb-0310-9956-ffa450edef68
QPID-4390: Store configuration entry attributes as top level fields inside of configuration entry and remove 'attributes' field

git-svn-id: https://svn.apache.org/repos/asf/qpid/branches/java-broker-config-qpid-4390@1429739 13f79535-47bb-0310-9956-ffa450edef68