GCM Json format issue

[sheldondz]

There is an issue with the regestration_ids format the current format outputs

"registration_ids":{"0":"APA91bF_ak3iCnF6x-NGygVyxGYosVnRG03vmKq_NnxPKfB..."}

which is incorrect the format should be

"registration_ids":["APA91bFeCHk8-ZgPNgKXwxwOhP6ozGMLhofn37ccF5ZPaNZwAIp2..."]

line 152 following code needs to be updates
foreach($this->payload['registration_ids'] as $key) {
$this->payload['registration_ids'] = $key . ',';
}
$this->payload['registration_ids'] = array(substr($this->payload['registration_ids'],0,-1));