1.2
  - jwt_encode_sig() now allows to override the typ field via headers #15
  - jwt_decode functions now check the 'exp' and 'nbf' fields and raise
    and error if token has expired.

1.1
  - Allow for empty list attributes in jwt_claim(), issue #13

1.0
  - jwt_encode_sig() and jwt_decode_sig() now use proper 64bit signatures
    as described in the spec (instead of openssl DER structures)

0.2
  - jwt_encode_hmac() and jwt_encode_sig() gain a 'header' parameter
  - Add spell checker, update maintainer email address