OAuth plugin does not grab key from JWK properly

[jvlians]

The OAuth plugin in its current state fails to grab any valid JWK. The reason for this is that it evaluates the wrong property on the keys object. Here is the getJWK() function in its current state:

function getPEM(decodedToken, keys) {
    var i = 0;
    debug('jwk kid ' + decodedToken.headerObj.kid);
    for (; i < keys.length; i++) {
        if (keys.kid == decodedToken.headerObj.kid) {
            break;
        }
    }
    var publickey = rs.KEYUTIL.getKey(keys.keys[i]);
    return rs.KEYUTIL.getPEM(publickey);
}

Note how this function tries iterating over keys at its root, and accessing keys.kid, but keys is not iterable at its root, nor does it have any properties apart from keys. The structure of keys is (in my case) as follows:

{
    "keys": [
        {
            "kty": "RSA",
            "alg": "RS256",
            "kid": "99gMqQi7UIfDqij_JX_RoNkC-bU-vlGQGwXoKWbGoes",
            "use": "sig",
            "e": "AQAB",
            "n": "gDf_fZFQrmZw14aHvJWb2SaQ30XBzYqu40SRFBgGGg-2TGRJD5rKbehPWGfZpYw2UEp2-aYw2-pFzAJF4SfFo3IjsU2tM5kEFCUreJdDW0II7ZaGaxXFcyteX7ULGErdZkX8w98Zay8abOegJpsDr8UBgJ0wNIpXx_nEe_ttrj3XexJ9ximJkrHvg4X9_mYhghOO5BbernrjEkeZo1ioQj4Q_H-Cn-DUwODr9b6NJ46qvo1UrKij13Q4lNNftUgvRQy0wNCUUNNgAZpVJOruMS9DUdCv5MGjgVsW7_KLHfUj0-di19XSRrQHyK_wh22gqzUoPaj-rVmqzQ1itkELWw"
        },
        {
            "kty": "RSA",
            "alg": "RS256",
            "kid": "luIheUMdlhacSF0zk2-tNDA7qd3sns_l21arS59FX-8",
            "use": "sig",
            "e": "AQAB",
            "n": "xh8tmPpzytiEfmBOn1oA20hH2TSLTcRdZprXK4tKuWnhiBz__E_qGusFf8lAA9tN9BZM_YptLRd6fjKjbRv1D8XUEqgwQoUVI9oNK-WvaZL0ZT1AIzbP5wUN-5uxOhwczp-nQ_R7IYjED_v1snHQRNf4W-8295UzjdHwTr29cw2wdLDsnSvgtwpHd9zpcCXaFkQ6-g9M8OariL0jL7KPCUSpb1e9E-Swmq6af2E8Peq9B68Ecys2Jf1iw24oIncS-vg9ZGuq4F5MASKmLVDjbBIrU2lQ3muK6JrakKQYxqVMnaS6vR-U3bEp7CcuGo-sfRZTZT6RYusJSy2GNLutYw"
        }
    ]
}

Thus, the function should iterate over keys.keys, or keys should be populated by the keys object in this JSON object.

I've already submitted a PR that resolves this issue, and adds support for situations like https://www.googleapis.com/oauth2/v1/certs . This PR can be found here: #87