Refactor hooks file.

It was long and rambly. It's also in need of unittesting. So split
it into some classes so that we can test the inputs and outputs
more sensibly.

Change-Id: I3d28f5771e38b819f98a9af06aeb06529be7b302

pbr/hooks/backwards.py

@@ -0,0 +1,34 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2013 Hewlett-Packard Development Company, L.P.
+# 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.
+
+from pbr.hooks import base
+from pbr import packaging
+
+
+class BackwardsCompatConfig(base.BaseConfig):
+
+    section = 'backwards_compat'
+
+    def hook(self):
+        self.config['include_package_data'] = 'True'
+        packaging.append_text_list(
+            self.config, 'dependency_links',
+            packaging.parse_dependency_links())
+        packaging.append_text_list(
+            self.config, 'tests_require',
+            packaging.parse_requirements(
+                ["test-requirements.txt", "tools/test-requires"]))