Make HyperlinkedModelSerializer `url` field name customizable
Override HyperlinkedModelSerializerOptions url field name with URL_FIELD_NAME setting
Test for customizable HyperlinkedModelSerializer url field name
More HyperlinkedModelSerializer docs
Use api_settings.URL_FIELD_NAME
Merge branch 'master' of git://github.com/sprymak/django-rest-framework into sprymak-master
Merge branch 'master' of https://github.com/tomchristie/django-rest-framework