Run wallpaper sink tests on Windows only

The wallpaper sink is currently only supported on Windows, therefore it doesn't make sense to execute its testsuite on other platforms

Author: w-enterprises

AllMyLights.Test/Connectors/WallpaperSinkTest.cs

@@ -1,3 +1,4 @@
+#if Windows
 using System.Collections.Generic;
 using System.IO;
 using AllMyLights.Connectors.Sinks.Wallpaper;
@@ -80,6 +81,7 @@ public void Should_prepend_configured_directory_to_relative_paths()
             desktopMock.Verify(it => it.SetBackground(expected));
         }
 
+        
         [Test]
         public void Should_prepend_configured_directory_to_relative_paths_for_each_display()
         {
@@ -101,4 +103,5 @@ public void Should_prepend_configured_directory_to_relative_paths_for_each_displ
             desktopMock.Verify();
         }
     }
-}
+}
+#endif

AllMyLights/Platforms/Windows/IDesktopWallpaper.cs

@@ -1,7 +1,5 @@
 using System;
-using System.Collections.Generic;
 using System.Runtime.InteropServices;
-using System.Text;
 
 namespace AllMyLights.Platforms.Windows
 {

AllMyLights/Platforms/Windows/WindowsDesktop.cs

@@ -1,12 +1,7 @@
-using AllMyLights.Extensions;
-using System;
+using System;
 using System.Collections.Generic;
-using System.Drawing;
-using System.Drawing.Imaging;
-using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
-using System.Windows.Forms;
 
 namespace AllMyLights.Platforms.Windows
 {