[BUG] [Proposal] SQL hook has no attribute 'set_up'

[Patataman]

SQL Hooks (and MongoHooks as far as I have seen) are splitted into 2 different methods:

def sumUrl_set_up(*args, **kwargs):
        tables = ["url_hourly", "url_daily", "url_monthly"]
        create_tables(tables, **kwargs)

def sumUrl(**kwargs):
    if not _check_environment(**kwargs):
        return
    if not _check_postgresql(**kwargs):
        raise NotImplementedError("Only PostgreSQL currently supported")
        return
    [...]

However in the Storage class method __init__ it is called as the following:

flask-track-usage/src/flask_track_usage/storage/__init__.py

Line 66 in 629ad1c

hook.set_up(**kwargs)

Two solutions came to my mind:

1. Change Storage.__init__ to call <hook>_set_up function instead.
2. Change how hooks are created to be classes instead methods