• Add support for the "nbf" (Not Before) Claim by @skion.
• Add support for encoding Plaintext JWTs (decode them with verify=False) by @skion.
• Add support for Elliptic Curve signatures (ES256 / ES384 / ES512) by @sullivanmatt.
• Fix import and reference of datetime functions in README by @glarrain.
• Add support for the "aud" (Audience) Claim.
• Add support for the "iss" (Issuer) Claim.