Factor out Gravatar hash calculation

(imported from commit 29872722fb4856773d98fc987a1e2d6eb99ad8b2)

zephyr/lib/avatar.py

@@ -0,0 +1,5 @@
+import hashlib
+
+def gravatar_hash(email):
+    """Compute the Gravatar hash for an email address."""
+    return hashlib.md5(email.lower()).hexdigest()

zephyr/models.py

@@ -10,6 +10,7 @@ import os
 import simplejson
 from django.db import transaction
 from zephyr.lib import bugdown
+from zephyr.lib.avatar import gravatar_hash
 
 @cache_with_key(lambda self: 'display_recipient_dict:%d' % (self.id))
 def get_display_recipient(recipient):
@@ -219,7 +220,7 @@ class Message(models.Model):
                 'subject'          : self.subject,
                 'content'          : content,
                 'timestamp'        : calendar.timegm(self.pub_date.timetuple()),
-                'gravatar_hash'    : hashlib.md5(self.sender.user.email.lower()).hexdigest(),
+                'gravatar_hash'    : gravatar_hash(self.sender.user.email),
                 }
 
     def to_log_dict(self):

zephyr/views.py

@@ -19,6 +19,7 @@ from django.views.decorators.csrf import csrf_exempt
 
 from zephyr.decorator import asynchronous
 from zephyr.lib.query import last_n
+from zephyr.lib.avatar import gravatar_hash
 
 from confirmation.models import Confirmation
 
@@ -26,7 +27,6 @@ import datetime
 import simplejson
 import socket
 import re
-import hashlib
 import urllib
 import time
 
@@ -186,7 +186,7 @@ def home(request):
 
     return render_to_response('zephyr/index.html',
                               {'user_profile': user_profile,
-                               'email_hash'  : hashlib.md5(user_profile.user.email).hexdigest(),
+                               'email_hash'  : gravatar_hash(user_profile.user.email),
                                'people'      : people,
                                'streams'     : streams,
                                'have_initial_messages':