Add secure-rbac tests for SecretStores API

This patch adds basic RBAC test for the Secret Stores API for
the reader, member and admin personas with project scope.

The tests are skipped by a config option, as they require
the multiple-backends feature to be enabled in barbican.

The devstack instace we're using for gate tests does not have
this enabled, so we default to False for now.

Change-Id: Ibca9d44fb3d0f4fd9945a7e6c636e0fbf6beb42e
diff --git a/barbican_tempest_plugin/config.py b/barbican_tempest_plugin/config.py
index 67a7986..7b79cb5 100644
--- a/barbican_tempest_plugin/config.py
+++ b/barbican_tempest_plugin/config.py
@@ -20,6 +20,17 @@
                              help="Whether or not barbican is expected to be "
                                   "available")
 
+barbican_tempest_group = cfg.OptGroup(
+    name='barbican_tempest',
+    title='Key Manager (Barbican) service options'
+)
+
+BarbicanGroupOpts = [
+    cfg.BoolOpt('enable_multiple_secret_stores',
+                default=False,
+                help="Flag to enable mulitple secret store tests")
+]
+
 ephemeral_storage_encryption_group = cfg.OptGroup(
     name="ephemeral_storage_encryption",
     title="Ephemeral storage encryption options")