Add support for roles in zuul

This adds support for Ansible roles in Zuul-managed repos.  It
is currently limited to repos within the same source, which is
something we should fix.

We also plan to add support for roles from Ansible Galaxy in a
future change.

Change-Id: I7af4dc1333db0dcb9d4a8318a4a95b9564cd1dd8
diff --git a/tests/unit/test_v3.py b/tests/unit/test_v3.py
index dd812a8..27e2275 100644
--- a/tests/unit/test_v3.py
+++ b/tests/unit/test_v3.py
@@ -155,3 +155,6 @@
         post_flag_path = os.path.join(self.test_root, build.uuid +
                                       '.post.flag')
         self.assertTrue(os.path.exists(post_flag_path))
+        bare_role_flag_path = os.path.join(self.test_root,
+                                           build.uuid + '.bare-role.flag')
+        self.assertTrue(os.path.exists(bare_role_flag_path))