Product/704 basic reporting

coscine/issues#704

src/Database/Models/KpiModel.cs

+using Coscine.Database.DataModel;
+using Coscine.Database.Util;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Coscine.Database.Models
+{
+    public class KpiModel : DatabaseModel<Kpi>
+    {
+        public override System.Linq.Expressions.Expression<Func<Kpi, Guid>> GetIdFromObject()
+        {
+            return (KpiObject) => KpiObject.Id;
+        }
+
+        public override LinqToDB.ITable<Kpi> GetITableFromDatabase(CoscineDB db)
+        {
+            return db.Kpis;
+        }
+
+        public override void SetObjectId(Kpi databaseObject, Guid id)
+        {
+            databaseObject.Id = id;
+        }
+
+        public int MarkAsSent(Kpi databaseObject)
+        {
+            databaseObject.SentSuccessfully = true;
+            return Update(databaseObject);
+        }
+    }
+}