* Fixes for Parser tests (was broken with new load balancing system), added LBFactory...

* Fixes for Parser tests (was broken with new load balancing system), added LBFactory::destroy() to destroy the singleton instance and force reopening a connection with the new value of $wgDBprefix.
* Added new globals to override:
** $wgGroupPermissions : restore default value for anons, some tests don't pass if anons aren't allowed to edit (there isn't "edit section" links)
** $wgDefaultExternalStore : don't use external sotrage since there isn't a table extdb.parsertest_blobs