Request example 1:
 POST /v1/token HTTP/1.1
 Content-Type: application/x-www-form-urlencoded
 Accept: application/json
 grant_type=client_credentials&client_id=test&client_secret=abc123

$url = "someUrl";
$ch = curl_init();

$username = "someUser";
$password = "somePass";

$post = json_encode(array(('grant_type'=>'client_credentials'));

curl_setopt($ch, CURLOPT_USERPWD, $username . ":" . $password);
curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS,$post);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
$result = curl_exec($ch);
curl_close($ch);