Added dr-dynamic-fields to requirements

requirements.txt

@@ -2,6 +2,7 @@ django-cors-headers~=2.1.0
 django-extensions~=1.7.7
 djangorestframework-jwt~=1.11.0
 djangorestframework~=3.6.3
+drf-dynamic-fields~=0.2.0
 Django~=1.11.8
 gevent~=1.2.2
 gunicorn~=19.7.0