Python 3 is stricter about how files are accessed. Specficially:
* Use open(), not file()
* Use binary mode for binary files (when checksumming)
* Use with statements to ensure files get closed
* Add missing file close statements
(Bitbake rev: 9f08b901375ba640f47596f1bcf43f98a931550f)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>