message: Add missing isMasterTokenRenewable() function.
diff: }, this);
  },
  + /** @inheritDoc */
  + isMasterTokenRenewable: function(ctx, masterToken, callback) {
  + AsyncExecutor(callback, function() {
  + if (!masterToken.isDecrypted())
  + return MslError.MASTERTOKEN_UNTRUSTED;
  + return null;
  + }, this);
  + },
  +
  /** @inheritDoc */
  renewMasterToken: function(ctx, masterToken, encryptionKey, hmacKey, issuerData, callback) {
  AsyncExecutor(callback, function() {
  