Upgrade to .net framework 4.0

Wox.Core/Updater/UpdaterManager.cs

@@ -0,0 +1,31 @@
+using Squirrel;
+
+namespace Wox.Core.Updater
+{
+    public class UpdaterManager
+    {
+        private static UpdaterManager instance;
+
+        public static UpdaterManager Instance
+        {
+            get
+            {
+                if (instance == null)
+                {
+                    instance = new UpdaterManager();
+                }
+                return instance;
+            }
+        }
+
+        private UpdaterManager() { }
+
+        public void CheckUpdate()
+        {
+            using (var mgr = new UpdateManager("https://path/to/my/update/folder", "nuget-package-id", FrameworkVersion.Net45))
+            {
+                 mgr.UpdateApp();
+            }
+        }
+    }
+}