Grants should be the default ones

When a node is not handled by PbT, or it doesn't have any terms related to it, Drupal Core adds for it some default grants. When this node is translated and the translation is set as not published, those grants are removed and not added back for the original (or the published) translation. This is because the current node being saved is not published. Drupal core doesn't care about node's status when the hook_node_grants hook is implemented, so we need to take care of this case in the PbT module.