Improved PushBullet implementation (v2 API, multiple devices, channels)

New: PushBullet supports multiple devices
New: PushBullet channels

Closes #641

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

@@ -0,0 +1,16 @@
+using System;
+using NzbDrone.Common.Exceptions;
+
+namespace NzbDrone.Core.Notifications.PushBullet
+{
+    public class PushBulletException : NzbDroneException
+    {
+        public PushBulletException(string message) : base(message)
+        {
+        }
+
+        public PushBulletException(string message, Exception innerException, params object[] args) : base(message, innerException, args)
+        {
+        }
+    }
+}