According to upstream (https://github.com/felixge/node-dateformat/issues/21) "dateformat() doesn't really play well with timezones since the javascript Date() object itself doesn't really play well with timezones."
We should be content with fixing the tests for the GMT timezone using the trick suggested by kapouer (https://github.com/felixge/node-dateformat/issues/41#issuecomment-286419133): TZ=GMT mocha -R spec Paolo
