QPID-6108: [Java Broker Documentation]  Rewrite HA documentation to reflect the new model and the include multi-node support.

* Correct many spelling errors
* Improve web-console documentation around add/edit/delete entities, and the setting of context variables
* Extract new top level section for backup/recovery

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1631195 13f79535-47bb-0310-9956-ffa450edef68
QPID-6108: [Java Broker Documentation]  Fix erroneously duplicated id in docbook

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1631199 13f79535-47bb-0310-9956-ffa450edef68