Add specific claims to token 

Example snippet when creating

```
JWT.create()
    .withClaim("name", 123)
    .withArrayClaim("array", new Integer[]{1, 2, 3})
    .sign(Algorithm.HMAC256("secret"));
```

Reading the claim

```
Map<String, Claim> claims = jwt.getClaims();    //Key is the Claim name
Claim claim = claims.get("name");

```