Code review comment for lp:~gmb/launchpad/bugzilla-3.4-dbtime

This branch adds the ability to get the time from the remote server to
the BugzillaAPI ExternalBugTracker.

I've added a local implementation of the API method that we call so that
we can test properly without having to connect to an actual instance as
well as the implementation of getCurrentDBTime() itself. I've made some
minor changes to TestBugzillaXMLRPCTransport.time() to make it a little
more readable.

= Launchpad lint =

Checking for conflicts. and issues in doctests and templates.
Running jslint, xmllint, pyflakes, and pylint.
Using normal rules.

Linting changed files:
  lib/lp/bugs/doc/externalbugtracker-bugzilla-api.txt
  lib/lp/bugs/externalbugtracker/bugzilla.py
  lib/lp/bugs/tests/bugzilla-xmlrpc-transport.txt
  lib/lp/bugs/tests/externalbugtracker.py