add_action('customize_register', 'themename_customize_register');

function themename_customize_register($wp_customize) {

    $wp_customize->add_section('ignite_custom_logo', array(
        'title' => 'Logo',
        'description' => 'Display a custom logo?',
        'priority' => 25
    ));

    $wp_customize->add_setting('custom_logo', array(
        'default' => ''
    ));

    $wp_customize->add_control(new WP_Customize_Image_Control($wp_customize, 'custom_logo', array(
        'label' => 'Custom logo',
        'section' => 'ignite_custom_logo',
        'settings' => 'custom_logo'
    )));

}