Fix ldap_backend and puppet 4.6

On xenial after update from puppet-agent 1.5 to 1.6, which include an
upgrade from 4.5 to 4.6 of puppet this code stopped working.

The ensure_resource in the keystone/init.pp manifest was not evaluated.
Adding this include seems to make it work again and we see that is the
log:

```
     Debug: Resource keystone_config[identity/domain_specific_drivers_enabled] was not determined to be defined
     Debug: Create new resource keystone_config[identity/domain_specific_drivers_enabled] with params {"value"=>true}
```

while without the include ::keystone, it's not there.

Puppet guru needed as to the why.

Change-Id: Ief78d70b8fe114ddf40d98fab93374862d3c23cb

manifests/ldap_backend.pp

@@ -459,6 +459,7 @@ define keystone::ldap_backend(
 ) {
 
   include ::keystone::deps
+  include ::keystone
 
   $domain_enabled = getparam(Keystone_config['identity/domain_specific_drivers_enabled'], 'value')
   $domain_dir_enabled = getparam(Keystone_config['identity/domain_config_dir'], 'value')

spec/defines/keystone_ldap_backend_spec.rb

@@ -1,10 +1,15 @@
 require 'spec_helper'
 
 describe 'keystone::ldap_backend' do
+  let :facts do
+    @default_facts.merge({ :osfamily => 'Debian' })
+  end
   describe 'Using Default domain' do
     let(:title) { 'Default' }
+
     let(:pre_condition) do
       <<-EOM
+      class { '::keystone': admin_token => 'token'}
       keystone_config {'identity/domain_specific_drivers_enabled': value => true}
       keystone_config {'identity/domain_config_dir': value => '/etc/keystone/domains'}
       file {'/etc/keystone/keystone.conf': ensure => present }
@@ -204,6 +209,7 @@ describe 'keystone::ldap_backend' do
     end
     let(:pre_condition) do
       <<-EOM
+      class { '::keystone': admin_token => 'token'}
       keystone_config {'identity/domain_specific_drivers_enabled': value => true}
       keystone_config {'identity/domain_config_dir': value => '/etc/keystone/domains'}
       file {'/etc/keystone/keystone.conf': ensure => present }
@@ -220,6 +226,7 @@ describe 'keystone::ldap_backend' do
     context 'Missing identity/domain_specific_drivers_enabled' do
       let(:pre_condition) do
       <<-EOM
+      class { '::keystone': admin_token => 'token'}
       keystone_config {'identity/domain_config_dir': value => '/etc/keystone/domains'}
       file {'/etc/keystone/keystone.conf': ensure => present }
       EOM
@@ -230,6 +237,7 @@ describe 'keystone::ldap_backend' do
     context 'Missing identity/domain_config_dir' do
       let(:pre_condition) do
       <<-EOM
+      class { '::keystone': admin_token => 'token'}
       keystone_config {'identity/domain_specific_drivers_enabled': value => true}
       file {'/etc/keystone/keystone.conf': ensure => present }
       EOM