Added new template filter: model_field_verbose_name
Added model_method_verbose_name util function
Show verbose column name in list view (fixes #236)
Added model_attr_verbose_name template filter.

Renamed the model_field_verbose_name to model_attr_verbose_name in
order to handle both fields and methods.
Merge branch 'iss236' of git://github.com/dbrgn/django-admin2 into dbrgn-iss236
Show verbose column name in list view (fixes #236)
Merge branch 'iss236' of git://github.com/dbrgn/django-admin2 into develop
Merge branch 'dbrgn-iss236' into develop
Merge branch 'develop' of github.com:twoscoops/django-admin2 into develop