* Add flags field in OBB footer to support overlays.
* Remove unused 'crypto' and 'filesystem' fields in obbtool (could
later be supported in the "flags" field of the OBB footer).
* Add notes to document OBB classes before shipping.
Change-Id: I386b43c32c5edef55210acb5d3322639c08010ba
Add "obbtool" host command for adding, removing, and querying Opaque
Binary Blob (OBB) information from a file.
Change-Id: Id2ac41e687ad2a500c362616d6738a8ae7e8f5c3