Add a vulnerability_found event for notice when we detect a vuln

Fixes #637

Note: This PR does *not* actually raise the event; it merely adds support for it

data/database.py

@@ -751,6 +751,7 @@ class RepositoryNotification(BaseModel):
   method = ForeignKeyField(ExternalNotificationMethod)
   title = CharField(null=True)
   config_json = TextField()
+  event_config_json = TextField(default='{}')
 
 
 class RepositoryAuthorizedEmail(BaseModel):