Enforcer enable_log insanity

[mconigliaro]

The enable_log parameter in Enforcer() makes it difficult to specify your own logging handlers. If you enable that option, your logs will get configured the way the casbin devs want them instead of the way you want them. If you leave that option disabled, they explicitly disable the casbin.enforcer logger for some reason, so those messages will never appear.

Solution:

1. Leave enable_log disabled:

   enforcer = Enforcer("model.conf", "policy.csv")

2. Re-enable the casbin.enforcer logger yourself:

   logging.getLogger("casbin.enforcer").disabled = False

3. Now you can add your own logging handlers

   logging.getLogger("casbin.enforcer").addHandler(RichHandler())
   logging.getLogger("casbin.enforcer").setLevel(logging.INFO)

[hsluoyz]

@mconigliaro can you make a PR to improve it?