Fix barbican_tempest option group

This patch fixes a bug with the barbican_tempest option group that was
breaking tempest init by returning the wrong object.

Change-Id: Ia62c43fc67114c89be5f481dab2cb11df6ee82b0
diff --git a/barbican_tempest_plugin/plugin.py b/barbican_tempest_plugin/plugin.py
index f320007..8f57374 100644
--- a/barbican_tempest_plugin/plugin.py
+++ b/barbican_tempest_plugin/plugin.py
@@ -57,7 +57,7 @@
             (project_config.key_manager_group.name,
              project_config.KeyManagerOpts),
             (project_config.barbican_tempest_group.name,
-             project_config.barbican_tempest_group),
+             project_config.BarbicanGroupOpts),
             (project_config.ephemeral_storage_encryption_group.name,
              project_config.EphemeralStorageEncryptionGroup),
             (project_config.image_signature_verification_group.name,