QPID-5803: [Java Broker] Add ability for the virtualhostnode to create a virtualhost using a blueprint supplied by context variable

* This commit reenables the SplitStoreTest.
* The UI has not been refactored by this commit, so it will not be possible to create a non-HA virtualhost from the UI
  (the UI will create only a virtualhostnode).. REST API is okay.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1601163 13f79535-47bb-0310-9956-ffa450edef68