Fixed many=False issue on related fields

Compat requestfactory secure

RequestFactory.generic()

Set dynamic maximum height for dropdown widgets

argument is not available

provided by django

Based on feedback on the pull request, changed solution to
be simpler for issue 3042

Document per-view versioning settings

Consistent 2 space tabbing and formatting

Added check to pop many from kwargs before passing to __init__
Fixed my lint issue from the previous commit

Adding failing test case when many=false is explicitly defined

https://github.com/tomchristie/django-rest-framework/issues/3042

Fixed minor typo on viewsets.md

Handle invalid characters in "Authorization: token ..." headers

I'm not sure how the contribution policy for the docs is, but I thought it'd be faster to issue a pull request than reaching out to you guys/creating an issue for something so simple. Hope it's not a problem :)

Fix versioning urls

`format_suffix_patterns` is applied before the trailing slash.

Replace the former `get_filter_backends` by `filter_queryset`.

Primary key serialization

Adds a 'pk_field' parameter which can be used to proxy serialization and
deserialization of arbitrary primary key values.

Remove `django.conf.urls.pattern`

Set the filter_backends class variable in the DjangoFilterBackend docs

Fix set_rollback on @transaction.non_atomic_requests.

This reverts commit e095b91f.

Include correct limits in LimitOffsetPagination link urls