Preserve attachment point & position when attachment is rezzed in world

Patch taken from
http://opensimulator.org/mantis/view.php?id=4905
originally by Greg C.

Fixed to apply to r/23314 commit
ba9daf849e7c8db48e7c03e7cdedb77776b2052f
(cherry picked from commit 4ff9fbca441110cc2b93edc7286e0e9339e61cbe)
Don't use 'Indented' formatting for RpcXml responses.
(cherry picked from commit 93abcde69043b175071e0bb752538d9730433f1d)