Update hacking and fix hacking violations

This does a few things:

* Update hacking to the version in global-requirements. Old hacking was
  installing a version of pbr that was breaking other packages.

* Fix all the hacking/pep8 rules that updating hacking raised.

* Do some general docstring cleanup, while already in there cleaning up
  a bunch of docstrings due to H405 violations.

Change-Id: I1fc1e59d4c3d7b14631f8b576e3f3854bc452188
Closes-Bug: #1461717

ironic_python_agent/encoding.py

@@ -42,8 +42,9 @@ class RESTJSONEncoder(json.JSONEncoder):
         return super(RESTJSONEncoder, self).encode(o) + delimiter
 
     def default(self, o):
-        """Turn an object into a serializable object. In particular, by
-        calling :meth:`.Serializable.serialize`.
+        """Turn an object into a serializable object.
+
+        In particular, by calling :meth:`.Serializable.serialize` on `o`.
         """
         if isinstance(o, Serializable):
             return o.serialize()