Update config templates to Havana release

Paste pipeline configuration moved to /etc/keystone/keystone-paste.ini,
which is included in openSUSE / SLES Havana packages. A templated
version is added just in case it's needed for other distributions.

LDAP attributes:
  Dropped: user_domain_id_attribute, group_domain_id_attribute
  Added:   user_default_project_id_attribute

The default for auth.methods changed from "password,token" to
"external,password,token,oauth1"

Includes migration for LDAP changes in the schema.