[ADD] add partner_maiden_name module: It allows to add the maiden name field to the partner

Port of https://code.launchpad.net/~savoirfairelinux-openerp/partner-contact-management/partner-contact-management-base_contact_add_partner_maiden_name/+merge/204023

Previous Review:
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@yvaucher: 

> Sorry indeed something is missing
>
> Thanks for the reminder
>
> Correct me if I'm wrong but Maiden name is sexist and not accurate nor generic nowadays.
>
> You should find enough altenatives with:
> Maiden name -> birth name, surname at birth, original name, former name