added new file `signature.py` which contains (so far) a single class: SignatureVerification, which is returned from PGPKeyring.verify() and is comparable as a boolean.
added new file `signature.py` which contains (so far) a single class: SignatureVerification, which is returned from PGPKeyring.verify() and is comparable as a boolean.

SecurityInnovation/PGPy,J08nY/PGPy,SecurityInnovation/PGPy,J08nY/PGPy,SecurityInnovation/PGPy