[FIX] models: properly format load error

In case of foreign language, using unicode characters, the error message may be
badly formated.

e.g.
Unknown error during import: <class 'odoo.exceptions.AccessError'>: เฉพาะผู้ดูแลร..

insted of
Unknown error during import: <class 'odoo.exceptions.AccessError'>: (u'\u0e40\u0e09\u0e1e\u0e32\u0e30\u0e1c\u0e39

opw-766580

odoo/models.py

@@ -895,7 +895,7 @@ class BaseModel(object):
                 # avoid broken transaction) and keep going
                 cr.execute('ROLLBACK TO SAVEPOINT model_load_save')
             except Exception as e:
-                message = (_('Unknown error during import:') + ' %s: %s' % (type(e), unicode(e)))
+                message = (_('Unknown error during import:') + ' %s: %s' % (type(e), unicode(e.message or e.name)))
                 moreinfo = _('Resolve other errors first')
                 messages.append(dict(info, type='error', message=message, moreinfo=moreinfo))
                 # Failed for some reason, perhaps due to invalid data supplied,