Moved application code to the Application layer

Imported Win10 project
Code cleanup
WIP - Use common UWP services for Win8.1 and Win10

ModernKeePass10/Views/MainPageFrames/ImportExportPage.xaml.cs

@@ -0,0 +1,35 @@
+using System;
+using Windows.Storage.Pickers;
+using Windows.UI.Xaml;
+
+// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238
+
+namespace ModernKeePass.Views
+{
+    /// <summary>
+    /// The import/export page.
+    /// </summary>
+    public sealed partial class ImportExportPage
+    {
+        public ImportExportPage()
+        {
+            InitializeComponent();
+        }
+
+        private async void ImportFileButton_OnClick(object sender, RoutedEventArgs e)
+        {
+            var picker =
+                new FileOpenPicker
+                {
+                    ViewMode = PickerViewMode.List,
+                    SuggestedStartLocation = PickerLocationId.DocumentsLibrary
+                };
+            picker.FileTypeFilter.Add(".csv");
+
+            // Application now has read/write access to the picked file
+            var file = await picker.PickSingleFileAsync();
+            if (file == null) return;
+            
+        }
+    }
+}