QPID-5408 : throw exception on unknown connection URL parameter

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1550405 13f79535-47bb-0310-9956-ffa450edef68
NO-JIRA: Expanded the HA overview writeup, integrated with doxygen docs.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1550507 13f79535-47bb-0310-9956-ffa450edef68
Merge trunk into messaging-logging