ota: Remove cruft we don't care about

Skip the date check (downgrade to your content), and don't include
recovery in otapackages.
5.0.0 update: We want the recovery patchstuff back
fix up ota_from_target_files symlink detection.
make bacon and custom releasetool (for squished zips)

Change-Id: I4f61b6a6b9b8bab8582fa5423c4134c07af17606

Conflicts:
	core/Makefile
add support for custom releasetools

Conflicts:
	core/Makefile