Module to map tax product

Migraton for bazaar
It should use the `replacing` syntax (http://openerp-connector.com/api/api_backend.html?highlight=replacing#connector.backend.Backend.parent), but it should not replace directly `ProductImportMapper`, instead, it should replace a Mapper dedicated for the taxes, like it has been done here: https://github.com/OCA/connector-magento/blob/7.0/magentoerpconnect/product.py#L435