WIP DO NOT MERGE: add support for keystone::ldap

With packstack, I can pass in "global parameters" via hiera.  I'm not sure what to do here.  It seems like adding 40-odd class parameters to quickstack::keystone::common (and quickstack::pacemaker::keystone) isn't the right thing to do.
Oh, also, you may want to add a conditional constraint if you need ldap configured before endpoints are created (not sure if that is a requirement, but kind of sounded like it might be from what you said)