Overview of Changes:
* Change version numbering to match PEP-0440
* Unpadding happens after MAC validation to prevent padding oracle attacks
* Added Encoding options to all crypto operations to select whether or not
not encoding should be used.
* Python version setup improved for PyPi.
* AttachedSign with empty nonce now correctly functions.
While here limit python version to 2.x, because it doesn't build with 3.x
PR: 204576
Submitted by: douglas@douglasthrift.net (maintainer)
1c4d9cba5f