- Add zip_safe flag

- If database lag exceeds max lag, the API will still send 200, not 503.
  This was only added to documentation after bugzilla:31156.
  Ref. <https://www.mediawiki.org/wiki/Manual:Maxlag_parameter>
- In addition, Requests doesn't raise an exception when status code != 200
  unless raise_for_status() is called, so we should call that to catch
  any other 5xx errors such as Squid errors.
- Replace print statements with logging

Note that responses>=0.3.0 is needed to run the test suite now

As suggested in #52
Original auth mechanism introduced in #27
This change should retain backwards compability

This class provided workarounds for editing pages without 'writeapi'.
Since 'writeapi' has been enabled by default since MediaWiki 1.14,
and we require MediaWiki 1.16, it should no longer be needed. If
'writeapi' has been explicitly disabled, we should rather raise an
error, since this means that automatic edits are not welcome.