function cmdTestReverseAsync(s, cb) {
        var result = s.split("").reverse().join("");
        process.nextTick(function () {
            cb(null, result);
        });
    }
@private
Handler for test.reverseAsync command. Reverses the specified string
and then returns the result asynconously.
@param {string} s String to reverse.
@param {Function} cb Callback function of the form cb(err, response)