Use Run() instead of Start() to execute notification helpers

Using Start() but not waiting for the command to complete will leave dangling
defunct processes that can't be cleaned up until its parent dies.

Run() will wait for the command to finish, but cleans up after itself.

notify_unix.go

@@ -25,7 +25,7 @@ func Notify(title, message, appIcon string) error {
 		}
 
 		c := exec.Command(send, title, message, "-i", appIcon)
-		return c.Start()
+		return c.Run()
 	}
 
 	knotify := func() error {
@@ -34,7 +34,7 @@ func Notify(title, message, appIcon string) error {
 			return err
 		}
 		c := exec.Command(send, "--title", title, "--passivepopup", message, "10", "--icon", appIcon)
-		return c.Start()
+		return c.Run()
 	}
 
 	conn, err := dbus.SessionBus()