Adding a skeleton/refrence recipe for using a subset of the yocto
kernel tools against kernel git repositories.

Sample/reference configuration fragments, features and a patch are
provided and documented in the recipe.

From the recipe itself:

   Provides an example/minimal kernel recipe that uses the linux-yocto
   and oe-core kernel classes to apply a subset of yocto kernel
   management to git managed kernel repositories.

 Notes:

   kconfig(s): the kernel must be configured with a defconfig, or via
               configuration fragment(s). Either of these can be added
               via bbappend.
   patches: patches can be merged into to the source git tree itself, added
            using standard bbappend syntax or controlled via .scc feature
            descriptions (also via bbappends)

   example configuration addition:
            SRC_URI += "file://smp.cfg"
   example patch addition (for kernel v3.4 only):
            SRC_URI += "file://0001-linux-version-tweak.patch
   example feature addition (for kernel v3.4 only):
            SRC_URI += "file://feature.scc"

 Warning:

   Building the sample kernel tree (kernel.org) without providing any
   configuration will result in build or boot errors. This is not a bug
   it is a required element for creating a valid kernel.

[YOCTO #2397]

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>