The ->getAdapter() method does not set the adapter if passed in config options

`->getAdapter()` method of parent class `ZendOAuth\Client` is:

    public function getAdapter()
    {
        if (! $this->adapter) {
            $this->setAdapter($this->config['adapter']);
        }

        return $this->adapter;
    }

but here was:

    public function getAdapter()
    {
        return $this->adapter;
    }

replaced with:

    public function getAdapter()
    {
        return parent::getAdapter();
    }