Use the algorithm value, not the keyId for the algorithm field in the…

… signature string (#103)

lib/signer.js

@@ -208,7 +208,7 @@ RequestSigner.prototype.sign = function (cb) {
 
         authz = FormatAuthz('Signature ', {
           keyId: sig.keyId,
-          algorithm: sig.keyId,
+          algorithm: sig.algorithm,
           headers: self.rs_headers.join(' '),
           signature: sig.signature
         });