Improve custom attributes in Django itself.

[surister]

Right now we have custom options at the Meta class, example auto_refresh:

class RefreshModel(CrateModel):
    field2 = models.TextField()

    class Meta:
        app_label = "test_app"
        auto_refresh = True

But we are doing Metaclass shenanigans to a accomplish this due lo the lack of extensibility of the django internals.

More details in https://forum.djangoproject.com/t/allow-meta-class-to-have-extra-database-specific-options/40650/3

[surister]

For now we are going to keep it as it is, as it works. But the ideal solution is that django itself improves this, we can help by pushing it to the devs.