Remove service.start_container()

It has been an unnecessary wrapper around container.start() for a little while now, so we can call it directly.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

compose/cli/main.py

@@ -448,7 +448,7 @@ class TopLevelCommand(DocoptCommand):
             raise e
 
         if detach:
-            service.start_container(container)
+            container.start()
             print(container.name)
         else:
             dockerpty.start(project.client, container.id, interactive=not options['-T'])