Add remaining request logic

[mpatnode]

In short the ApiResponse copies the latest remainder count into the current client.

    $instagram = new Instagram\Instagram;
    $instagram->setClientID(INSIGHTS_INSTAGRAM_CLIENT_ID);

    / /  Make lots of requests....

    $count = $instagram->getRequestsRemaining();

    if ($count < 10) {
             //  Do something about it
    }