rearrange service startup a bit, now Node.startService() returns a Deferred that fires when the tub is actually ready, and there is also a Node.when_tub_ready() hook. This allows get_local_addresses() to be slow and not break everything. Changed all necessary test cases to accomodate this slow startup.

src/allmydata/test/test_storage.py

@@ -21,7 +21,8 @@ class StorageTest(unittest.TestCase):
         self.node.setServiceParent(self.svc)
         self.tub = Tub()
         self.tub.setServiceParent(self.svc)
-        return self.svc.startService()
+        self.svc.startService()
+        return self.node.when_tub_ready()
 
     def test_create_bucket(self):
         """