Following up on these discussions:
http://psf.upfronthosting.co.za/roundup/tracker/issue3532
http://www.gossamer-threads.com/lists/python/dev/863892

I'm submitting a patch to add bytes.hex method in accordance to PEP 358.
The code was taken from binascii so it should be "tested".
Also added bytearray.hex and fixed the documentation and testing.

There are additional things to discuss, for example:
* multiple and different implementations of tohex\fromhex - in binascii, sha1module, bytes, bytearray...
* binascii's functions which perform the same thing, but those functions and the rest of binascii's functions receive and return wrong types. I would fix this but it breaks compatibility.