Allow users to select any extra field as vehicle identifier.

Models/Vehicle.cs

@@ -28,5 +28,9 @@
         /// </summary>
         public string OdometerDifference { get; set; } = "0";
         public List<DashboardMetric> DashboardMetrics { get; set; } = new List<DashboardMetric>();
+        /// <summary>
+        /// Determines what is displayed in place of the license plate.
+        /// </summary>
+        public string VehicleIdentifier { get; set; } = "LicensePlate";
     }
 }

Models/VehicleViewModel.cs

@@ -15,6 +15,7 @@
         public bool OdometerOptional { get; set; } = false;
         public List<ExtraField> ExtraFields { get; set; } = new List<ExtraField>();
         public List<string> Tags { get; set; } = new List<string>();
+        public string VehicleIdentifier { get; set; } = "LicensePlate";
         //Dashboard Metric Attributes
         public List<DashboardMetric> DashboardMetrics { get; set; } = new List<DashboardMetric>();
         public int LastReportedMileage { get; set; }