board: add support for Intel Galileo Gen 2

Board support package includes:

 * Toplevel build root configuration
 * Github based 3.8.7 Kernel
  * Upstream 3.8.7
  * Linux 3.8.7 Kernel Driver Patches
 * Linux 3.8.7 configuration
 * Grub configuration
 * Init Script to load modules
 * genimage config to create sdcard image.

[Thomas: simplify post-image script since there is now only one call
to genimage.]

Signed-off-by: Ray Kinsella <ray.kinsella@intel.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>