fix OpenSSL-1.0.0 interop-test compatibility
fix OpenSSL-1.0.0 interop-test compatibility

The /usr/bin/openssl ECDSA sign/verify arguments changed. Now we use "-SHA1"
on openssl-1.0.0 and later, or "-ecdsa-with-SHA1" on earlier versions like
the common openssl-0.9.8o .

arnuschky/python-ecdsa,GreatFruitOmsk/python-ecdsa,alex/python-ecdsa,cornelinux/python-ecdsa,romanz/python-ecdsa