private async void SearchUserButton_Click(object sender, EventArgs e)
        {
            try
            {
                AuthenticationServiceClient client = new AuthenticationServiceClient();
                string roleName = comboBoxRole.Text;
                if (roleName.ToLower().Equals("all roles"))
                {
                    roleName = "";
                }
                Form frm = new ProgressForm();
                frm.Show();
                User[] users = await client.SearchUserAsync(textBoxLogin.Text, textBoxFullName.Text, roleName);

                frm.Close();
                dataGridViewSearch.DataSource = new BindingList <ClientUser>(users.Select(user => new ClientUser(user)).ToList());
                if (users.Length == 0)
                {
                    MessageBox.Show("Users not found!");
                }
            }
            catch (FaultException exc)
            {
                MessageBox.Show(exc.Message);
            }
        }