Add helper for iterating over months and move date proxy here

the proxy is now needed by two commands

Author: rambo

project/asylum/utils.py

@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+import calendar
+import datetime
 import importlib
 import random
 
@@ -26,3 +28,19 @@ def get_random_objects(klass, num=1):
         random_index = random.randint(0, count - 1)
         ret.append(klass.objects.all()[random_index])
     return ret
+
+
+# Adapted from http://www.ianlewis.org/en/python-date-range-iterator
+def months(from_date=None, to_date=None):
+    from_date = from_date or datetime.datetime.now().date()
+    while to_date is None or from_date <= to_date:
+        yield from_date
+        from_date = from_date + datetime.timedelta(days=calendar.monthrange(from_date.year, from_date.month)[1])
+    return
+
+
+def datetime_proxy(delta=datetime.timedelta(days=1)):
+    """Used by management commands needing datetime X days ago"""
+    now_yesterday = datetime.datetime.now() - delta
+    start_yesterday = datetime.datetime.combine(now_yesterday.date(), datetime.datetime.min.time())
+    return start_yesterday.isoformat()