Moving security-consider discussions to the security-services list

Hi,

as part of handing off the leading of the SAML security considerations work to
Chris McClaren, Chris & I've decided that we're going to freeze this
distribution list (security-consider), and have any further discussions on the
security-services list. the archives for this list will remain available for
future reference. 

since there's been very little to no discussion on this list for quite a while,
it shouldn't prove to be a disruption. 

However, if you're subscribed to this list, but not this security-services list,
you may want to subscribe to the latter. 

thanks,

JeffH & Chris