Add CSS clas to BxDolProfileFields.php

Add code highlighted in red. Mo better this way.... trust me.

@ line 1338

        // add submit button
        $aInputs[] = array(
            'type' => 'submit',
            'name' => 'do_submit',
            'value' => _t( '_Join_now' ),
            'attrs' => array(
	    'class' => 'bx-btn-primary join_now'
        	),
            'colspan' => false,
        );