common: parse/format dates in HumanReadableObjects

closes #229

circle/common/models.py

@@ -32,6 +32,7 @@ from django.core.serializers.json import DjangoJSONEncoder
 from django.db.models import (
     CharField, DateTimeField, ForeignKey, NullBooleanField
 )
+from django.template import defaultfilters
 from django.utils import timezone
 from django.utils.encoding import force_text
 from django.utils.functional import Promise
@@ -428,6 +429,14 @@ class HumanReadableObject(object):
             admin_text_template = admin_text_template._proxy____args[0]
         self.user_text_template = user_text_template
         self.admin_text_template = admin_text_template
+        for k, v in params.iteritems():
+            try:
+                v = timezone.datetime.strptime(
+                    v, "%Y-%m-%dT%H:%M:%S.%fZ").replace(tzinfo=timezone.UTC())
+            except ValueError:
+                pass
+            if isinstance(v, timezone.datetime):
+                params[k] = defaultfilters.date(v, "DATETIME_FORMAT")
         self.params = params
 
     @classmethod