add support for building flashable kernel zips

choose device from lunch menu then enter make bootzip, builds flashable boot.img with updated source ramdisk

Change-Id: I07820d5e5e48d5b973901ed2bb3f330744c6498c

Conflicts:
	core/Makefile
make bootzip: add support for loki patch

patchset 2:
   whitespace
Change-Id: I4a757f7483e3bea1b4dad981f8236bb9551e9eca

Conflicts:
	core/Makefile
make bootzip: convert bash to python

Change-Id: Ie5d3e6d07df7f46df3717b9203b6f70edf208cb1

Conflicts:
	core/Makefile
	tools/releasetools/boot_flash_from_image