Use js escaping for buttons 'text' property, so it can contain html tags

[yoshi-1]

-- corrected branch original PR #629 ---

Hi,
i suggest to change the default html escaping of the buttons text in the twig template, so that it's possible to use html tags for styling the text eg. with an icon like this:

$this->extensions->set(array(

       		'buttons' => array(
            	'create_buttons' => array(
                	array(
                    	'action' => array(
                        	'template' => ':post:action.js.twig',
                        	//'vars' => array('id' => '2', 'test' => 'new value'),
                    	),
                    	'text' => '<i class="fa fa-plus"></i> New',
                	),
            	),
       		),
        ));

[mshd]

This is useful, I found a workaround if somebody needs it urgently

"button_options" => [
                      "text" => "<span class='glyphicon glyphicon-wrench'></span>"