[MERGE] [FIX] l10n_be_invoice_bba: correctly create bba reference when creating an invoice

  When creating an invoice from another object (sale: invoice from sale order
  line, sale: invoice on delivery order, ...) we have to make sure that newly
  created invoice respect partner's default ``communication type``, and
  accordingly generate a new BBA if required and none provided.

  backport of v7.0 revid: xal@openerp.com-20130624083322-h3h4h8nn876585m3