v2.4.0

• Add support for Django REST Framework 3.7.x.
• Add support for Django 2.0.
• Drop support for Django 1.8 - 1.10 (EOL)
• Drop support for Django REST Framework < 3.6.3
  (3.6.3 is the first to support Django 1.11)
• Drop support for Python 3.3 (EOL)