Code review comment for lp:~allenap/launchpad/remove-xmlrpclib-marshalling-bug-254999

Removes the xmlrpclib.DateTime() hacks in the external bug tracker code, as it's not needed with the version of xmlrpclib in Python 2.5. I've also done a fair bit of de-linting, but it's still a small change so I haven't broken it out into a separate patch.