Fix download/upload timeout + Fix some warnings

OpenSaveCloudClient/Core/SaveManager.cs

@@ -22,13 +22,16 @@ namespace OpenSaveCloudClient.Core
             ThreadPool.QueueUserWorkItem(delegate { CleanArchiveFolder(); });
         }
 
-        public static SaveManager GetInstance()
+        public static SaveManager Instance
         {
-            if (instance == null)
+            get
             {
-                instance = new SaveManager();
+                if (instance == null)
+                {
+                    instance = new SaveManager();
+                }
+                return instance;
             }
-            return instance;
         }
 
         public GameSave Create(string name, string path, string coverHash)