simplify database lookup code by using the find-database method
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.
Use the right attribute for the keystone group
Merge pull request #135 from mapleoin/find-database

simplify database lookup code by using the find-database method
Only allow one keystone-server node

Allowing more makes nearly no sense, as the endpoint in keystone can
only point to one node.
Use new validation API in validate_proposal_after_save
Stop using validate_has_active_database_proposal

We actually don't need this:
 - if we just save without applying, we don't need to check this
 - if we save and apply but the database proposal is not active, then
   the keystone proposal will be queued (which is the right behavior)
Use new find_dep_proposal helper
Merge pull request #126 from saschpe/release/roxy/master-havana-config

Update config templates to Havana release
Merge pull request #156 from vuntz/validation

Use new helpers to create/validate proposals
Merge pull request #154 from vuntz/use-group

Use the right attribute for the keystone group