Added support for Django 1.5's pluggable User model.
Removed audit fields.

Removed the audit fields to make reuse easier. Instead of simply adding the
fields a complete audit solution should have been implemented. However
that makes reusing the model in another project awkward at best since a
different auditing solution might be used. Instead it is better to rely on third
part apps such as django-reversion that can easily be implemented in the
final site so a single auditing model is used for all the apps used in the project.
Updated load_checklists to distinguish between added and updated checklists.

The status report generated by the load_checklists management command
now contains separate sections listing the checklists that were newly added
from those that were updated. This makes it easier to see when an editor
should review the new incoming records for publication.

Furthermore the section for updated checklists only contains those where the
data was changed. If a checklist is reloaded with no changes then it does not
appear in the report (previously it did). Again this makes it easy to see when an
editor should review the records for publication.
Updated changelog for 0.4.9
Updated version number for release
Merge branch 'release-0.4.9' into develop