Fix bugs, mostly related to date formatting.

endpoints/api/webhook.py

@@ -1,3 +1,5 @@
+import json
+
 from flask import request, url_for
 from flask.ext.restful import abort
 
@@ -74,4 +76,4 @@ class Webhook(RepositoryParamResource):
     log_action('delete_repo_webhook', namespace, 
                {'repo': repository, 'webhook_id': public_id},
                repo=model.get_repository(namespace, repository))
-    return make_response('No Content', 204)
+    return 'No Content', 204