Aria G25 u-boot, up-to-date kernel, qemu, aiccu, and various minimal images

Important additions:

* U-boot is specifically enabled for the Aria G25 from Acme Systems.
* The at91bootstrap bootloader hands over control to u-boot.

May safely be ignored:

* QEMU was updated because it wouldn't build on my Intel i7.
* The various images may be ignored.
* Aiccu (for SixXS) isn't required, and should be moved to some other recipe meta-folder.

The last three have been removed from my meta-atmel branch in my most recent commit; you may want to pull that one instead.