[New] Added New l10n_it_base refactored and new l10n_it_pec

Hi!
as discuss on https://github.com/OCA/l10n-italy/issues/2 I made this pull request.

The l10n_it_base now is a simple configuration module.
I created a l10n_it_pec that add a field for mail on the partner profile after the normal mail

Regards

Franco
I tried the module removing the overriden create method (https://github.com/drdran/l10n-italy/pull/1) and I didn't find problems.
I would not introduce an extra hack if we don't need it for now.