Add BaseAPITestCase class that invalidates the permission and smart settings caches.

Use BaseAPITestCase for all API test cases.

mayan/apps/rest_api/tests/base.py

@@ -0,0 +1,17 @@
+from __future__ import absolute_import, unicode_literals
+
+from rest_framework.test import APITestCase
+
+from permissions.classes import Permission
+from smart_settings.classes import Namespace
+
+
+class BaseAPITestCase(APITestCase):
+    """
+    API test case class that invalidates permissions and smart settings
+    """
+
+    def setUp(self):
+        super(BaseAPITestCase, self).setUp()
+        Namespace.invalidate_cache_all()
+        Permission.invalidate_cache()