Changed default kernel;modified UBI volume in U-Boot

Changed back to the 3.6.9 kernel for the system while working
on getting the SPI port working.  Changed the bootargs in U-Boot
to reflect the newly set UBI_VOLNAME of rootfs.
Adjusting U-Boot to make all partitions writable.  Added pkg_postinst to re-write U-Boot in flash.
Created packages for at91bootstrap and added pkg_postinst to re-write at91bootstrap in flash after upgrade.