fixed a bug of Loading

Storyboard will not pause if IsRunning is asigned a value of false in xaml

src/Shared/HandyControl_Shared/Controls/Loading/LoadingCircle.cs

@@ -180,6 +180,10 @@ namespace HandyControl.Controls
             }
 
             Storyboard.Begin();
+            if (!IsRunning)
+            {
+                Storyboard.Pause();
+            }
         }
 
         private Border CreateBorder(int index, double dotInterval, bool needHidden)

src/Shared/HandyControl_Shared/Controls/Loading/LoadingLine.cs

@@ -98,6 +98,10 @@ namespace HandyControl.Controls
             }
 
             Storyboard.Begin();
+            if (!IsRunning)
+            {
+                Storyboard.Pause();
+            }
         }
 
         private Ellipse CreateEllipse(int index, double dotInterval, double dotDiameter)