Fix crash when UAC blocks the program.

=_=英语不好连个说明和注释都写不出了

Wox.Plugin.System/Programs.cs

@@ -1,5 +1,6 @@
-using System;
+using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
@@ -51,9 +52,21 @@ namespace Wox.Plugin.System
                         MessageBox.Show("couldn't start" + c.Title);
                     }
                     else
+                    {
+                        try
                         {
                             Process.Start(c.ExecutePath);
                         }
+                        catch (Win32Exception)
+                        {
+                            //Do nothing.
+                            //It may be caused if UAC blocks the program.
+                        }
+                        catch (Exception e)
+                        {
+                            throw e;
+                        }
+                    }
                 }
             }).ToList();
         }