Add support for declaring named volumes in compose files

* Bump default API version to 1.21 (required for named volume management)
* Introduce new, versioned compose file format while maintaining support
  for current (legacy) format
* Test updates to reflect changes made to the internal API

Signed-off-by: Joffrey F <joffrey@docker.com>

tests/integration/state_test.py

@@ -26,10 +26,10 @@ class ProjectTestCase(DockerClientTestCase):
         details = config.ConfigDetails(
             'working_dir',
             [config.ConfigFile(None, cfg)])
-        return Project.from_dicts(
+        return Project.from_config(
             name='composetest',
             client=self.client,
-            service_dicts=config.load(details))
+            config_data=config.load(details))
 
 
 class BasicProjectTest(ProjectTestCase):