Add test for BooleanField and required

This tests setting required=True on a BooleanField.

Test for issue #1004.
Only HTML forms should have implicit default False for boolean fields
Merge branch 'boolean-field-required-1004' of git://github.com/willkg/django-rest-framework
Update release notes
improving documentation about object level permissions #1049
Include import paths throughout docs.

Closes #1051.  Thanks to @pydanny for the report.
Merge pull request #1050 from filipeximenes/master

Improving documentation about object level permissions #1049
Docs tweaking around `check_object_permissions`
Added @filipeximenes

For work on #1050.  Thanks!
If page size query param <= 0, just use default page size.

Closes #1028.
Merge master