Add obfuscate_url_pw() to db.util module.

This is just for convenience...I think.

rattail/db/util.py

@@ -35,6 +35,9 @@ from rattail.db import Session
 from rattail.db.changes import record_changes
 from rattail.util import load_object
 
+# This import is provided for caller convenience:
+from alembic.util import obfuscate_url_pw
+
 
 def engine_from_config(configuration, prefix='sqlalchemy.', **kwargs):
     """