Added a directory listing service for MUC rooms (jabber:iq:search). Applied the new search to the default MultiUserChatServer implementation, which can act as an example to any other implementation. Added service discovery identity and features to the service that reflect these changes.

git-svn-id: http://svn.igniterealtime.org/svn/repos/openfire/branches@9177 b35dd754-fafc-0310-a699-88a17e54d16e