Log Message:
Version 4.6
Add a CountryFieldMixin Django Rest Framework serializer mixin that \ 
automatically picks the right field type for a CountryField (both single and \ 
multi-choice).
Validation for Django Rest Framework field (thanks Simon Meers).
Allow case-insensitive .by_name() matching (thanks again, Simon).
Ensure a multiple-choice CountryField.max_length is enough to hold all countries.
Fix inefficient pickling of countries (thanks Craig de Stigter for the report \ 
and tests).
Stop adding a blank choice when dealing with a multi-choice CountryField.
Tests now cover multiple Django Rest Framework versions (back to 3.3).

Version 4.6.1
Fix invalid reStructuredText in CHANGES.