OF-2648: Restore restoration of stream namespaces
In OF-2556, a workaround was provided to 'restore' namespace declarations on a stream element that had been parsed during the setup of the session.
This workaround injected a prefix-less 'stream' element. Unless the original stream defined a default namespace, this will not properly be parsed by an XML parser.
In this commit, the prefix 'stream' is used for the injected element (which is a de-facto standard in XMPP), and, for good measure, the namespace for that prefix is added, if it wasn't already recorded before.
OF-2647: Restore JiveGlobals.getHomeDirectory(String)
A previous commit for OF-2647 replaced the argument to the getter and setter of `JiveGlobals.setHomeDirectory()` from a String to a Path.
In hindsight, the signature change was to much of a change. This commit 'undoes' that change, by:
- introducing `get/setHomePath(Path)` (instead of replacing `getHomeDirectory`)
- restoring `get/setHomeDirectory(String)` and marking it as being deprecated
This should restore backwards compatilibity, and give plugin implementors time to migrate from the old to the new API.
