Fixing nuspec to use AppVeyor output directory

Author: Keboo

MaterialDesignColors.nuspec

@@ -16,7 +16,7 @@
     <tags>WPF XAML WinRT Material Design Colour Color UI UX</tags>
   </metadata>
   <files>
-    <file src="MaterialDesignColors.Wpf\bin\Release\MaterialDesignColors.dll" target="lib\net45" />
-    <file src="MaterialDesignColors.Wpf\bin\Release\MaterialDesignColors.pdb" target="lib\net45" />
+    <file src="MaterialDesignColors.Wpf\bin\AppVeyor\MaterialDesignColors.dll" target="lib\net45" />
+    <file src="MaterialDesignColors.Wpf\bin\AppVeyor\MaterialDesignColors.pdb" target="lib\net45" />
   </files>
 </package>