NextGenListResource can now load first page and stop iterating when there is no next_page_uri.
NextGenListResource can now load first page and stop iterating when there is no next_page_uri.

twilio/twilio-php,FTrubitz/twilio-php,javierwilson/twilio-php,sayan801/twilio-php,Git-Host/twilio-php,achoe/twilio-php,pablophg/twilio-php