[IMP] product_import_cert modifications

[Ariel E. Figueroa - http://www.humanytek.com]

Hi:

Please make the next changes on product_import_cert module.

1. change the field source from char to many2one relation to res.country model
2. add a new field "Backgrounds" one2many telation res.country model
3. make the field "initial term" be editable in view form now is not editable see ... http://youtu.be/1UDFxKrHBh8
4. in list view show columns in from left to right in the next order:

4.1 Permit Number (Certificate Number)
4.2 Product
4.3 Manufacturer
4.4 Custom
4.5 Initial term
4.6 end term
4.7 State

5. This module need one new Dependencie module pls link the module l10n_mx_import_info, i request one improvement on this module pls see the bug 1401374

6. Once the improvement is done, inherit the model import.info.custom with all his data and change the field custom from char to many2one field, relation with import.info.custom (requested in bug 1401374)

Translate terms:
Backgrounds = Procedencias

Change terms in spanish
change "Cantidad importado" at "Saldo por importar"