Add get_request_data compat method

`request.DATA` was put on the deprecation path
in 3.0. It has now been removed and its
usage will result in an error.

Author: jpadilla

rest_framework_jwt/compat.py

@@ -47,3 +47,13 @@ def get_username(user):
         username = user.username
 
     return username
+
+
+def get_request_data(request):
+    try:
+        data = request.data
+    except:
+        # DRF < 3.2
+        data = request.DATA
+
+    return data

rest_framework_jwt/views.py

@@ -2,8 +2,8 @@
 from rest_framework import status
 from rest_framework.response import Response
 
-from rest_framework_jwt.settings import api_settings
-
+from .settings import api_settings
+from .compat import get_request_data
 from .serializers import (
     JSONWebTokenSerializer, RefreshJSONWebTokenSerializer,
     VerifyJSONWebTokenSerializer
@@ -52,7 +52,9 @@ def get_serializer(self, *args, **kwargs):
         return serializer_class(*args, **kwargs)
 
     def post(self, request):
-        serializer = self.get_serializer(data=request.DATA)
+        serializer = self.get_serializer(
+            data=get_request_data(request)
+        )
 
         if serializer.is_valid():
             user = serializer.object.get('user') or request.user