extend X509 and PKey object with modulus function

The attached patch implements the modulus function in both X509 & PKey objects.
Patch is developed against 0.10 release of pyOpenSSL

Thanks for the patch. Are you interested in writing some unit tests for these two new methods as well?

Adding the following code to test_crypto.py in the class X509ExtTests will perform a minimal self unittest of the modulus function.

    def test_modulus(self):
        """
        The modulus of the certificate and the private key should
        match
        """
        self.assertEqual(self.pkey.modulus(), self.x509.modulus())

I would love to see this patch accepted in the mainline. Do we need to test this any further?

I have no idea to be honest, the patch is running in productions since it was created (or actually before). There should be little issues with it, as it really is a wrapper around libssl.
So unittest are hard, as you want to test the function and not the libssl library.

That is way (in my opinion) a simple call test is sufficient