This adds initial support for building non-standard versions

This adds initial support for building non-standard versions
of the Linux kernel for openslug (or any NSLU2 distro).  The
.inc file nslu2-kernel.inc does work to decode ${PV} and work
out what patches to download.  The sole .bb file,
nslu2-kernel_2.6.11.8.bb, is just an example (which *does* work
and has been tested, slightly).  Non-release (mm, ac, rc) patches
have not been tested yet and may not work.
NOTE: this is for testing/dev of new kernels.  It is necessary to
set the PREFERRED_PROVIDER_virtual/kernel to nslu2-kernel to pull
these .bb files into a build.

BKrev: 427af2a47Q3EUuIjzVKXRDWBgDDKzw