Center empty favorites message. Give it some padding.

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

@@ -30,6 +30,8 @@
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:layout_weight="1"
+        android:gravity="center_horizontal"
+        android:paddingTop="10sp"
         android:text="@string/empty_favorites_list_message"
         android:visibility="gone" />