Basic pluto with IKEv2 using X.509 on the responder (east), and Strongswan on
the initiator (west).

This is the reverse test of interop-ikev2-strongswan-04-x509-responder

This is the basic test for Authentication method as Digital Signatures as 
specified in RFC 7427. Currently supported for RSA.

This includes a new notification of type SIGNATURE_HASH_ALGORITHMS. We currently
supoort SHA1 only.

