classes/image*: Revamp creation of live images

This creates a live image as an IMAGE_FSTYPES, thus removing the
need to have additional -live.bb recipes.  To create a live image
one just needs to add live to the IMAGE_FSTYPES list

(From OE-Core rev: b3ff63796cd6629975ff0a726ba18cc168e0a2b2)

Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/image-live.bbclass

@@ -0,0 +1,13 @@
+
+AUTO_SYSLINUXCFG = "1"
+INITRD = "${DEPLOY_DIR_IMAGE}/core-image-minimal-initramfs-${MACHINE}.cpio.gz"
+APPEND += "root=/dev/ram0 "
+TIMEOUT = "10"
+LABELS += "boot install"
+
+ROOTFS = "${DEPLOY_DIR_IMAGE}/${IMAGE_BASENAME}-${MACHINE}.ext3"
+
+do_bootimg[depends] += "core-image-minimal-initramfs:do_rootfs"
+do_bootimg[depends] += "${IMAGE_BASENAME}:do_rootfs"
+
+inherit bootimg