Correct a small typo in exceptions documentation

This is to address https://github.com/tomchristie/django-rest-raml/issues/5

The problem is that if you try to generate RAML docs when you haven't set up any views, you get the above error (min called on an empty list).  

unfortunately, this PR is not very helpful since it doesn't actually surface a readable error to the user.  Not sure what the best way to address this would be...

Bump release versions to 1.10.3, 1.9.11 and 1.8.16

More info on:

https://www.djangoproject.com/weblog/2016/nov/01/security-releases/

This change adds support to use `'autofocus': True` in the style options and have the `autofocus` attribute included on the input field when rendered.

Add documentation link for single 'field-level validation' to the Validator docs page (#3772) (#4657)

To do `GROUP_BY` queries in django requires one to use `.values()`
eg this groups posts by user getting a count of posts per user.

```
Posts.objects.order_by('user').values('user').annotate(post_count=Count('post'))
```

This would produce a value queryset which serializes its result
objects as dictionaries while `CursorPagination` requires a queryset
with result objects that are model instances.

This commit enables cursor pagination for value querysets.

- had to mangle the tests a bit to test it out. They might need
  some refactoring.
- tried the same for `.values_list()` but it turned out to be
  trickier than I expected since you have to use tuple indexes.

Since `str` objects are immutable, appending to existing `str` creates
in fact a new `str` instance.

Thus `ErrorDetail.detail.code` attribute is lost after `str` concatenation operation.

APIException has a get_full_details() method but the documentation refers to full_details().

Add `drf-proxy-pagination` reference to Pagination docs

when using with django-filter and rest_framework_swagger need to import coreapi before django-filter as django filter tries to load rest_framework.coreapi which is undefined at this point

... in section ModelSerializer 'fields' and 'exclude'

Deprecate the built-in `rest_framework.filters.DjangoFilterBackend` in favour of the third-party `django_filters.rest_framework.DjangoFilterBackend`.