[SSSD] Design Discussion: LDAP Referral Chasing

[Stephen Gallagher]

I've created the following wiki page with my thoughts on the design of
the LDAP referral chasing:
https://fedorahosted.org/sssd/wiki/DesignDocs/LDAPReferrals

Please review it and provide feedback in this email thread.

Pavel, please review this as well, as one section of the proposal may
affect your ticket #960 (though it's possible that your approach already
accounts for this).