var rof = typeof (ConfigurationElementCollection).GetField("bReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);
            rof.SetValue(ConfigurationManager.ConnectionStrings, false);

            ConfigurationManager.ConnectionStrings.Add(new ConnectionStringSettings
            {
                ConnectionString = Configuration["Data:DefaultConnection:ConnectionString"],
                Name = Configuration["Data:DefaultConnection:Name"],
                ProviderName = Configuration["Data:DefaultConnection:ProviderName"]
            });