Allow to use tiny-linux-bootloader

[piranna]

As commented on #273 (comment), being able to use tiny-linux-bootloader would make it easier to use NodeOS as a single-app OS but also to use it in some scenarios where it would make sense to have a single-user OS, like for example flashing it on a pendrive having the kernel and initram isolated from the pendrive filesystem instead of storing them on the same partition or having two of them on the USB drive.