Add otapackage support for backuptool

Change-Id: I512554c579d444067cd3ccbb0e6946a5eb6bc964a

Conflicts:
	core/Makefile
	tools/releasetools/ota_from_target_files

Conflicts:
	core/Makefile
	tools/releasetools/edify_generator.py
	tools/releasetools/ota_from_target_files
releasetools: backup

Conflicts:
	tools/releasetools/ota_from_target_files
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