Added outline color picker to sample page

Author: Alberto Fustinoni

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/RadialProgressBar/RadialProgressBarCode.bind

@@ -22,7 +22,8 @@
                   Minimum="0"
                   Maximum="100"
                   Width="@[Width:Slider:100:100-200]"
-                  Height="@[Height:Slider:100:100-200]"/>
+                  Height="@[Height:Slider:100:100-200]"
+                  Outline="@[Outline:Brush:LightGray]"/>
           </Grid>
       </Grid>
 </Page>

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/RadialProgressBar/RadialProgressBarPage.xaml

@@ -21,7 +21,8 @@
                                         Thickness="{Binding Thickness.Value, Mode=OneWay}"
                                         Value="{Binding Value.Value, Mode=OneWay}"
                                         Width="{Binding Width.Value, Mode=OneWay}"
-                                        Height="{Binding Height.Value, Mode=OneWay}"/>
+                                        Height="{Binding Height.Value, Mode=OneWay}"
+                                        Outline="{Binding Outline.Value, Mode=OneWay}"/>
         </Grid>
     </Grid>
 </Page>