Changed implementation of sample data

Creating a new entry does not create an useless history value
WIP import data

ModernKeePass/ImportFormats/NullImportFormat.cs

@@ -0,0 +1,13 @@
+using Windows.Storage;
+using ModernKeePass.Interfaces;
+
+namespace ModernKeePass.ImportFormats
+{
+    public class NullImportFormat: IFormat
+    {
+        public IPwEntity Import(IStorageFile source)
+        {
+            throw new System.NotImplementedException();
+        }
+    }
+}