Use different mixpanel tokens while deployed vs in development

(imported from commit 4fac466a822d49cb0e1a7592dbd77d8ee019803e)

zephyr/lib/response.py

@@ -1,6 +1,7 @@
 from __future__ import absolute_import
 
 from django.http import HttpResponse, HttpResponseNotAllowed
+from django.conf import settings
 import django.shortcuts
 import simplejson
 
@@ -30,5 +31,19 @@ def json_success(data={}):
 def json_error(msg, data={}, status=400):
     return json_response(res_type="error", msg=msg, data=data, status=status)
 
+# We wrap render_to_response so that we can always add some data to
+# the template context dictionary.  In particular, we add the
+# mixpanel token (which varies based on whether we're deployed or
+# not) because the mixpanel code is included in base.html.
 def render_to_response(template, *args, **kwargs):
+    if args:
+        dictionary = args[0]
+    else:
+        try:
+            dictionary = kwargs['dictionary']
+        except KeyError:
+            dictionary = {}
+            kwargs['dictionary'] = dictionary
+
+    dictionary['mixpanel_token'] = settings.MIXPANEL_TOKEN
     return django.shortcuts.render_to_response(template, *args, **kwargs)