[banshee] DateButton: Remove unneeded using statement

[Bertrand Lorentz <blorentz src gnome org>]

commit fc59f57c2bc4153d3ec5229f3e8d90c2c419d89b
Author: Bertrand Lorentz <bertrand lorentz gmail com>
Date:   Sat Oct 12 15:17:50 2013 +0200

    DateButton: Remove unneeded using statement
    
    This fixes the build with the latest gtk-sharp from git master, as GLib
    now has its own DateTime class, which would clash with System.DateTime.

 .../Banshee.Widgets/Banshee.Widgets/DateButton.cs  |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/src/Core/Banshee.Widgets/Banshee.Widgets/DateButton.cs 
b/src/Core/Banshee.Widgets/Banshee.Widgets/DateButton.cs
index 519a54a..9846f44 100644
--- a/src/Core/Banshee.Widgets/Banshee.Widgets/DateButton.cs
+++ b/src/Core/Banshee.Widgets/Banshee.Widgets/DateButton.cs
@@ -28,7 +28,6 @@
  */
 
 using System;
-using GLib;
 using Gtk;
 
 namespace Banshee.Widgets