Create a BootloaderInstallHelper class for handling post installation hints and
creating the installation instance depending on the player model. This removes
the base class handling its derived classes which always has been weird, and
removes the need to change the base class when adding a new installation
method, since the base shouldn't be affected.
Change-Id: I2a156d70fd1cff6c48bdd46d10c33d75c953ea90
