Distributed attribute-resolver.

[Rod Widdowson]

The currently shipped attribute-resolver.xml is pretty minimal, do we want
to include the full glory that is shipped with V2?  

If we do bring this forward we need to consider what to do about
$IDP_SCOPE$.  I'd favour making it a property (%{idp.scope}) defaulted to
example.org.

Then of course I need to push that configuration into the installer.  Is it
reasonable to just default it to the DNS name, or do we need to prompt the
used? It rather feels as though this needs to be prompted for.

Rod