/// <summary>
        /// Her bliver vores ønskede data gemt i vores database.
        /// </summary>
        /// <param name="billetId"></param>
        /// <param name="kundeId"></param>
        /// <param name="antalBorn"></param>
        /// <param name="antalStuderende"></param>
        /// <param name="antalVoksne"></param>
        /// <param name="dateTime"></param>
        /// <param name="pris"></param>
        /// <param name="sejltur"></param>
        // gemmer alle værdier i databasen
        public void Add(int antalBorn, int antalStuderende, int antalVoksne, DateTime dateTime, decimal pris, bool sejltur, string email, string navn, string telefonNr)
        {
            Kunde newKunde = new Kunde(email, navn, telefonNr);

            Kunder.Add(newKunde);
            PersistencyService.SaveKunderAsJsonAsync(newKunde);
            Billet newBillet = new Billet(PersistencyService.ID, antalBorn, antalStuderende, antalVoksne, new DateTime(dateTime.Year, dateTime.Month, dateTime.Day), pris, sejltur);

            Billeter.Add(newBillet);
            PersistencyService.SaveBilleterAsJsonAsync(newBillet);
        }
        /// <summary>
        /// LoadBilleterAsync loader data fra vores database tabel "Billeter".
        /// </summary>

        public async void LoadBilleterAsync()
        {
            var billeter = await PersistencyService.LoadBilleterFromJsonAsync();

            if (billeter != null)
            {
                foreach (var b in Billeter)
                {
                    Billeter.Add(b);
                }
            }
            else
            {
                //Data til testformål
                Billeter.Add(new Billet(1, 123456789, 123456789, 123456789, new DateTime(2015, 05, 14), 1234, false));
                Billeter.Add(new Billet(2, 123456789, 123456789, 123456789, new DateTime(2015, 05, 14), 1234, false));
            }
        }