Add INITIUM_BOOTDEV_OTHER boot device type to Initium specification
Add INITIUM_BOOTDEV_OTHER boot device type to Initium specification

This allows an arbitrary string to be specified as the boot device, the
meaning of which is OS-dependent. This allows boot devices that may be
recognised by the OS but not supported by the boot loader to be used.

gil0mendes/Initium,gil0mendes/Initium,gil0mendes/Initium