* `signWith()` & `setSigningKey()` now prefer to be handed a `Key` type rather than a base64-encoded
String - deprecated in jwtk/jjwt#341
* To obtain a configured `JwtParser`, a builder is now preferred, ie
  `Jwts.parserBuilder().setSigningKey(key).build()` rather than `Jwts.parser().setSigningKey(key)` - deprecated
  in jwtk/jjwt#486
* Use `io.jsonwebtoken.security.SignatureException` rather than
  `io.jsonwebtoken.SignatureException` - deprecated in jwtk/jjwt#367

Note that `play-googleauth` currently supports two versions of Play:

* Play v2.9, uses jjwt v0.11.5
* Play v3.0, uses jjwt v0.12.6

...we need to support both, but thankfully everything we're using is supported in both versions of jjwt.