Support PlayStation Mobile titles;

Sony [did it again](https://silica.codes/OpenPSS/sign_pss) and just gave away the private signing key for PlayStation Mobile games, this means that it should be possible to sign a PSM game you don't own using the keys for a PSM game you do own; (i.e the thing chovy-sign already does for PSP games..) the biggest issue with this idea is you would need to legitimately own a PSM game on PSN, which is nearly impossible to do today, but, it still might be useful for some.