rootfs_rpm.bbclass: added from Poky

rootfs_rpm.bbclass: added from Poky

Squashed changes from Poky:

svn r5101 - Add rootfs_rpm.bbclass, a start at image generation from rpms. Its
            not expected to be entirely functional yet.
svn r5112 - rootfs_rpm.bbclass: Remove the feed directory before packaging the image
svn r5134 - rootfs_rpm.bbclass: Add basic postinstall handling during image creation
svn r5143 - rootfs_rpm.bbclass: Fixup broken symlinks due to fakechroot and run
            any leftover postinstalls on real hardware at first boot
svn r5158 - rootfs_rpm.bbclass: Add recommends handling
svn r5380 - rootfs_rpm.bbclass: ship rpm and yum in target images
svn r5382 - rootfs_rpm.bbclass: Add rpm package coverage
svn r5386 - rootfs_rpm.bbclass: use more efficient way to copy packages
svn r5391 - rootfs_rpm: set target architecture and do not tell yum which arch we will use
svn r5398 - rootfs_rpm.bbclass: Set YUM_ARCH_FORCE
svn r5412 - rootfs_rpm.bbclass: remove lock files to get rpm working on device
svn r5432 - rootfs_rpm.bbclass: fix platform so rpm will be usable on device
svn r5433 - rootfs_rpm.bbclass: remove temporary yum config - rootfs has one
            from yum package
svn r5434 - rootfs_rpm.bbclass: added generation of feed entries
svn r5436 - rootfs_rpm.bbclass: added code to generate images from feeds

OE changes:

rootfs_rpm.bbclass: remove two functions (need rewrite for RPM)

install_all_locales and remove_packaging_data_files functions were from
rootfs_ipk.bbclass and need to be rewritten for RPM rootfs.

rootfs_rpm.bbclass: use DISTRO instead of hardcoded Poky - spotted by Tom Rini
rootfs_rpm.bbclass: drop not needed disabled code