added Matthias Erll to contributors since he did initial work for DRF3 support which I based my implementation on [ci skip]

AUTHORS.rst

@@ -13,6 +13,7 @@ Contributors
 * Davide Mendolia - https://github.com/davideme
 * Kevin Brown - https://github.com/kevin-brown
 * Martin Cavoj - https://github.com/macav
+* Matthias Erll - https://github.com/merll
 * Mjumbe Poe - https://github.com/mjumbewu
 * Thomas Wajs - https://github.com/thomasWajs
 * Xavier Ordoquy - https://github.com/xordoquy