SAN with NULL byte in dNSName

[tiran]

Ruby, Python and PHP were vulnerable to NULL bytes in subject alt name. I fixed the bug for Python and PHP (CVE-2013-4238, CVE-2013-4238, http://bugs.python.org/issue18709).

You may not be able to produce a vulnerable certificate with OpenSSL. I tried but failed. Eventually I used some Ruby code to produce a vulnerable certificate.

[lgarron]

As with #52, I'm happy to make the repo work for esoteric test cases (that don't break anything else) if people are willing to implement them in the script.