Support for Ed25519 Certificates

[thmang82]

The original implementation did not support pure ed25519 based certificates with Ed25519 signing algorithm (OID: 1.3.101.112)

This PR consists of two small changes:

• X509: Ed25519 does not verify based on hash => return 'none' for Ed25519
• PKI: in verify, when 'none' for hash, verify based on data instead of hash