add logout button and use default album art in more locations

app/src/main/res/layout/item_grid.xml

@@ -3,6 +3,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_margin="2dp"
     android:foreground="?rectSelectorStrong">
 
@@ -23,6 +24,7 @@
                 android:layout_width="match_parent"
                 android:layout_height="match_parent"
                 android:scaleType="centerCrop"
+                app:srcCompat="@drawable/default_album_art"
                 tools:ignore="ContentDescription" />
 
         </com.kabouzeid.gramophone.views.WidthFitSquareLayout>