In light of future devices in need of special images for initial
flashing which are, in contrast to factory images, only flashable
from the bootloader, we add a new category for images which don't fit
into factory nor sysupgrade.
Devices in need for those images contain the AVM Fritz!Box 4040 and
various TP-Link Mediatek models.
Example for the Fritz!Box 4040:
> other -squashfs-eva.bin bootloader.bin
results in the eva image landing in the "other" folder suffixed with
"bootlaoder.bin".
