Move RbacAuthority class into separate module

This patchset simply moves the RbacAuthority abstract base class
into its own module for better code organization.

Change-Id: I89bee142671645f304d622b9e6c25fbab745a7e2
diff --git a/patrole_tempest_plugin/rbac_authority.py b/patrole_tempest_plugin/rbac_authority.py
new file mode 100644
index 0000000..294ecc5
--- /dev/null
+++ b/patrole_tempest_plugin/rbac_authority.py
@@ -0,0 +1,38 @@
+# Copyright 2017 AT&T Corporation.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import abc
+
+import six
+
+
+@six.add_metaclass(abc.ABCMeta)
+class RbacAuthority(object):
+    """Class for validating whether a given role can perform a policy action.
+
+    Any class that extends ``RbacAuthority`` provides the logic for determining
+    whether a role has permissions to execute a policy action.
+    """
+
+    @abc.abstractmethod
+    def allowed(self, rule, role):
+        """Determine whether the role should be able to perform the API.
+
+        :param rule: The name of the policy enforced by the API.
+        :param role: The role used to determine whether ``rule`` can be
+            executed.
+        :returns: True if the ``role`` has permissions to execute
+            ``rule``, else False.
+        """