Change vehicle taxation

see https://life-of-german.org/bugtracker/bug/60-neue-fahrzeugsteuern/

@hydrant update DB before merge with master.

ReallifeGamemode.Database/Entities/UserVehicle.cs

@@ -15,10 +15,13 @@ namespace ReallifeGamemode.Database.Entities
   {
     [ForeignKey("User")]
     public int UserId { get; set; }
+
     public User User { get; set; }
 
     public int? Price { get; set; }
 
+    public int? BusinessId { get; set; }
+
     public override string ToString()
     {
       return "Spieler Fahrzeug | Besitzer: " + GetOwner().Name;