use toplevel makefile to build bsdiff and puffdiff dependencies
use payload_dumper.py to extract payload.bin from differential update
checksums supplied in payload.bin are tested but not enforced (mismatches are printed to screen)
Parameters
diff -- apply differential update - abort if diff fails to apply
fakediff -- apply differential update but ignore failing diffs and fill missing parts with 0xEF - extracts some useful information from payload without having original image