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/ironic_api_client.py

@@ -91,8 +91,9 @@ class APIClient(object):
         return node_content
 
     def _do_lookup(self, hardware_info):
-        """The actual call to lookup a node. Should be called inside
-        loopingcall.BackOffLoopingCall.
+        """The actual call to lookup a node.
+
+        Should be called as a `loopingcall.BackOffLoopingCall`.
         """
         path = '/{api_version}/drivers/{driver}/vendor_passthru/lookup'.format(
             api_version=self.api_version,