make liquid and custom releasetool (for squished zips)

Change-Id: I4f61b6a6b9b8bab8582fa5423c4134c07af17606
add support for custom releasetools

Signed-off-by: Chet Kener <Cl3Kener@gmail.com>

Conflicts:
	core/Makefile
build: Fix usage of releasetool

Conflicts:
	core/Makefile
build: Run squisher for the liquid target

Change-Id: If33402a5eb1661345c7d37ec1778742096449c70

Conflicts:
	core/Makefile
TARGET_CUSTOM_RELEASETOOL is a squisher replacement

Change-Id: I9c7126d6bbe0303c1d35bb54ec2f0c9187b131e0

Conflicts:
	core/Makefile