A simpler, SQLAlchemy-specific fixture loader
>>> import fixer
>>> f = FixtureLoader(metadata)
>>> f.init_db(drop=True)
>>> f.load(list_of_fixtures)
>>> f = FixtureLoader(metadata)
>>> f.setup(list_of_fixtures)
>>> with FixtureLoader(metadata) as f:
... do_something_with_the_db()