Fix line endings in upgrade rules files

- Use unix line endings
- No "\n" at the end of a message

OpenRA.Mods.Common/UpdateRules/UpdateUtils.cs

@@ -9,7 +9,7 @@
  */
 #endregion
 
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;