Update BeagleBone README with more up-to-date information
about this particular board.
Allow ubldr and the associated loader.help file to be
installed separately.  In particular, BeagleBone wants
the loader.help to be on the UFS partition and ubldr itself
is on the MSDOS partition.
Install ubldr to MSDOS partition and the associated
help file to the UFS partition.
Updates to README to better match the current state of affairs.
Fix cpio command to preserve all permissions.
Allow specific board configs to override the final instructions.
VersatilePB support, thanks to Takeshi Taguchi.