image.mk: introduce Image/Build/UbinizeImage make target

paramters:
$(1) board name
$(2) ubinize-image options (e.g. --no-kernel and/or --uboot-env)
$(3) rootfstype (e.g. squashfs or ubifs)
$(4) kernel image file
$(5) options to pass-through to ubinize (i.e. $($(PROFILE)_UBI_OPTS)))

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

SVN-Revision: 41311