Feed error messages through a cors wrapper so that people on other domains can see what's happening.

endpoints/api/webhook.py

@@ -1,10 +1,9 @@
 import json
 
 from flask import request
-from flask.ext.restful import abort
 
 from endpoints.api import (RepositoryParamResource, nickname, resource, require_repo_admin,
-                           log_action, validate_json_request, api)
+                           log_action, validate_json_request, api, NotFound)
 from data import model
 
 
@@ -63,7 +62,7 @@ class Webhook(RepositoryParamResource):
     try:
       webhook = model.get_webhook(namespace, repository, public_id)
     except model.InvalidWebhookException:
-      abort(404)
+      raise NotFound()
 
     return webhook_view(webhook)