Allow label escape disabling like native Zend\Form\View\Helper\FormRow

This code modification allow user to disable the label html escape with the label options. For example : 

$form->add(array(
	            'type' => 'Zend\Form\Element\Text',
	            'name' => 'element',
        		'options' => array(
	            		'label' => 'Element <span>Label</span> :',
        				'label_options' => array('disable_html_escape' => true)
        		)
        ));
Merge pull request #84 from BnitoBzh/patch-1

Allow label escape disabling like native Zend\Form\View\Helper\FormRow