title: Odoo: Change invoice.line
body: <p>By default Odoo adds Product-Title and Product-Description to the Invoice order.line Description.</p>
  
  <p>I would like to have it slightly different:</p>
  
  <p>Product Title (aka name)
  Product-Variants (p.ex.  red, size L and so on...)</p>
  
  <p>How do i do that?
  I found a module that comes close, but somehow i'm Stuck!
  <a href="https://www.odoo.com/apps/modules/8.0/account_invoice_line_description/" rel="nofollow">https://www.odoo.com/apps/modules/8.0/account_invoice_line_description/</a></p>
  
  <p>Here is the relevant code from the module i found - It adds the Product Description to the order.line.description --> So changing that to product title and Variants should not be that hard... should... i need help.</p>
  
  <p>Thank you very much!</p>
  
  <pre><code>class AccountInvoiceLine(models.Model):
  _inherit = "account.invoice.line"
  
  @api.multi
  def product_id_change(
          self, product, uom_id, qty=0, name='', type='out_invoice',
          partner_id=False, fposition_id=False, price_unit=False,
          currency_id=False, company_id=None
  ):
      res = super(AccountInvoiceLine, self).product_id_change(
          product, uom_id, qty=qty,
          name=name, type=type, partner_id=partner_id,
          fposition_id=fposition_id, price_unit=price_unit,
          currency_id=currency_id,  company_id=company_id
      )
      if product:
          if self.user_has_groups(
                  'account_invoice_line_description.'
                  'group_use_product_description_per_inv_line',
          ):
              product = self.env['product.product'].browse(product)
              if product.description:
                  if 'value' not in res:
                      res['value'] = {}
                  res['value']['name'] = product.description
      return res
  </code></pre>