API urls need to be updated

[AndLeeDavis]

Old URL:

`public function getCampaignInfo($id)
{
if (empty($id)) {
return $this->handleError('Empty campaign id');
}

    $requestResult = $this->sendRequest('campaigns/' . $id);

    return $this->handleResult($requestResult);
}

`

Latest Works:

`public function getCampaignInfo($id)
{
if (empty($id)) {
return $this->handleError('Empty campaign id');
}

    $requestResult = $this->sendRequest('push/tasks/' . $id);

    return $this->handleResult($requestResult);
}

`
See - https://sendpulse.com/integrations/api/web-push#statistics