[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
In my opinion, such a  CHANGES.md  file is hard to keep up to date and does not provide further informations. We have the commits that give us those informations