Added missing colon in extra_kwargs documentation

Add Sentry as a premium sponsor.

It is possible that a key in a MultiValueDict has multiple values, lists
are represented this way. When accessing a key in a MultiValueDict
it only returns the last element of that key. This becomes a problem
when parsing an html dict with a list inside of it.

To fix this problem we have to get and set the value using .getlist()
and .setlist().

Support nested namespaces with namespaced versioning.

* Robust uniqueness checks
* Add master to test matrix (allow_failures)

* Test against Django 1.10b1
* Test against Django master

* Prevented unnecessary distinct() call in SearchFilter.

* Refactored SearchFilter lookup prefixes.

README sponsorship placement.

Make offset_cutoff a class attribute in CursorPagination so that it can be easily overridden in subclasses (#4212)

Make the usage of httpie accept headers more explicit.

* Simplfy TimeField passing through strings

* Exclude read_only=True fields from unique_together validation
* Test to ensure that unique_together validators can be removed
* Do not add uniquness_extra_kwargs when validators are explicitly declared.
* Add docs on validation in complex cases

Removed unnecessary `AUTH_USER_MODEL` compat variable.

(No longer required)

upgraded django to 1.9.7 release

* Add Meta.fields = '__all__' to serializer classes where required.
* Add explicit on_delete=models.CASCADE to ForeignKey fields.
* Use '.remote_field' and '.model' in preference to '.rel' and '.to' when inspecting model fields.
* Use new value_from_object in preference to internal _get_val_from_obj

Update filtering.md

* updated guardians and filter versions
* Remove Django 1.10 from allow_failures

Do not list related field choices in OPTIONS requests.