New: PushBullet to all devices (leave device id blank)

src/NzbDrone.Core/Notifications/PushBullet/PushBulletSettings.cs

@@ -11,7 +11,6 @@ namespace NzbDrone.Core.Notifications.PushBullet
         public PushBulletSettingsValidator()
         {
             RuleFor(c => c.ApiKey).NotEmpty();
-            RuleFor(c => c.DeviceId).NotEmpty();
         }
     }
 
@@ -22,7 +21,7 @@ namespace NzbDrone.Core.Notifications.PushBullet
         [FieldDefinition(0, Label = "API Key", HelpLink = "https://www.pushbullet.com/")]
         public String ApiKey { get; set; }
 
-        [FieldDefinition(1, Label = "Device ID", HelpText = "device_iden in the device's URL on pubshbullet.com")]
+        [FieldDefinition(1, Label = "Device ID", HelpText = "device_iden in the device's URL on pubshbullet.com (leave blank to send to all devices)")]
         public String DeviceId { get; set; }
 
         public bool IsValid