Don't use a deprecated API

coin/vpn/views.py

@@ -2,7 +2,7 @@ import os
 from urllib2 import urlopen
 
 from django.contrib.auth.models import User
-from django.http import HttpResponse
+from django.http import StreamingHttpResponse
 from django.shortcuts import render_to_response, get_object_or_404
 from django.views.generic.detail import DetailView
 from django.conf import settings
@@ -50,4 +50,4 @@ def get_graph(request, vpn_id, period="daily"):
                 "target=alias%%28scaleToSeconds%%28vpn1.%(login)s.uptxbytes%%2C1%%29%%2C%%20%%22Upload%%22%%29&" \
                 "title=VPN%%20Usage%%20%(login)s" % \
                     { 'period': time_periods[period], 'login': vpn.login })
-    return HttpResponse(urlopen(graph_url), mimetype="image/png")
+    return StreamingHttpResponse(urlopen(graph_url), content_type="image/png")