You can get your Client ID from your App on Twitch (see this blog)
But see below for the updated line, you need to make sure to declare the $clientID as well:
$clientID = 'CLIENTIDHERE'
$dataArray = json_decode(file_get_contents('https://api.twitch.tv/kraken/streams?channel=' . $callAPI . '&client_id=' . $clientID, false, stream_context_create($arrContextOptions)), true);