updated SSA schema for the registry

[Ray Plante]

Hi RWGers, DALers, and SSA enthusiasts,

The IVOA twiki page, SsaResourceSchema, has the latest SSA extension 
schema posted as SSA-wd.xsl.  If there are no further comments on this, we 
will release it as an external working draft and begin using it in our 
registries.

On advice of the SSA spec editor, this latest version distinguishes 
pre-1.0 implemenatations from truely v1.0 compliant is with different 
capability xsi:types: "SimpleSpectralAcces" for post 1.0 versions and 
"ProtoSpectralAccess."  Please review the section labeled, "Representing 
v1.0 and pre-1.0 Implementations".

LAST CHANCE FOR COMMENTS!

thanks!
Ray