Added plugin unloading

src/Artemis.Plugins.LayerTypes.Brush/BrushLayerType.cs

@@ -1,4 +1,5 @@
-using System.Drawing;
+using System;
+using System.Drawing;
 using Artemis.Core.Plugins.Interfaces;
 using Artemis.Core.ProfileElements;
 using QRCoder;
@@ -17,6 +18,11 @@ namespace Artemis.Plugins.LayerTypes.Brush
             var qrGenerator = new QRCodeGenerator();
         }
 
+        public void DisablePlugin()
+        {
+            throw new NotImplementedException();
+        }
+
         public void Update(Layer layer)
         {
             var config = layer.LayerTypeConfiguration as BrushConfiguration;