Cleaning up GFK test module.  Refs #607.
Test for GFK, using RelatedField.  Refs #607.
Update docs/tutorial/4-authentication-and-permissions.md

HTMLFormatter is in pygments.formatters.html
Merge pull request #614 from guglielmo/patch-1

Update docs/tutorial/4-authentication-and-permissions.md
Added @guglielmo, for the tutorial fix in #614.  Thanks!
Fix pagination docs
Serializers should accept source='*' argument. Fixes #604.

(Test also incoming)
Fix issues with custom pagination serializers
Test for custom pagination serializers.  Also refs #604.
Version 2.1.17