add settings to toggle fuel decimals from three to two.

Models/UserConfig.cs

@@ -9,6 +9,7 @@
         public bool EnableAuth { get; set; }
         public bool HideZero { get; set; }
         public bool UseUKMPG {get;set;}
+        public bool UseThreeDecimalGasCost { get; set; }
         public string UserNameHash { get; set; }
         public string UserPasswordHash { get; set;}
     }