Add option for disabling "first request decorator" (setupmethod) decorator

Sometimes it is unavoidable to raise the assertion added in SHA: 5500986971b28f270a27db633acf19984eee609e

For example the scenario described here:
http://blog.madflex.de/2012/1/17/FlaskSQLAlchemy_PostgresqlConnector/

There should be an option to disable the assertion even in debug mode.