https://github.com/Redth/PushSharp
https://github.com/Redth/PushSharp/wiki/How-to-Configure-&-Send-Apple-Push-Notifications-using-PushSharp
https://github.com/Redth/PushSharp/wiki/How-to-Configure-&-Send-GCM-Google-Cloud-Messaging-Push-Notifications-using-PushSharp