[ADD] Parse the request and response to ease debug

1. Also the requests are stored and enable to trace posible errors
2. When the invoice is not received with success there is no error, store the problems in ws.request.errors and enable the user to retry later.

models/ws.py

@@ -26,7 +26,7 @@ class ws_request(models.Model):
         ws_url = (self.env['ir.config_parameter'].sudo().get_param('financing.ws.url') or 'http://servicioscpz.credipaz.com/wsMIL/wsMIL.asmx') + '?WSDL'
         ws_client = Client(ws_url)
         try:
-            self.xml_res = ws_client.service.RegistrarVentaMil(sUsuario='odoo', sPassword='OdooP4sswd', sPin='20', xmlVenta=self.xml_req)
+            self.xml_res = ws_client.service.RegistrarVentaMil(sUsuario='odoo', sPassword='OdooP4sswd', sPin='203', xmlVenta=self.xml_req)
         except Exception as e:
             self.write({
                 'errors_ids': [(0, 0, {'name': _('Connection Error'), 'desc': e})]