Release 3.1.2

Allow DjangoObjectPermissions to use views that define get_queryset

minor grammar fix

Adding django-versatileimagefield to DRF 3rd party docs

Closes WGBH/django-versatileimagefield#12

Added link to djangorestframework-word-filter package

update info about wq.db.rest router

Separate LICENSE and README to two files.

Document correct method usage for get_paginated_response

Delete imported but not used method

Delete imported but not used method

 In 'Generating Tokens' section, the example code imported get_user_model but not used.

Fixed description for get_paginated_response method in generic-views and example using it with @list_route decorator in viewsets.

Fix Invalid keyword model with generic views

DateField to_representation can handle str and empty values. Fixes #2656, #2687.

of old get_pagination_serializer only valid in 2.x

Depth should reduce on nested ModelSerializer classes.

Merge pull request #2757 from ekiourk/2630/Raise-exception-when-ModelSerializer-used-with-abstract-model

Raise error when ModelSerializer used with abstract model

Update 5-relationships-and-hyperlinked-apis.md

Move ul.breadcrumb margin to bootstrap-tweaks.css

Check AcceptHeaderVersioning with content negotiation in place

Remove mention of Django's built-in ValidationError in docstring

The `exception_handler` does not actually handle django.core.exceptions.ValidationError, so remove any mention of it.

This closes #2872

Frontpage example no longer uses model attribute

Prevent empty `queryset`s to raise AssertionError.