Added ability to set html to popup message

Set html templates to skip escaping HTML in block title, question
zones, blocks and feedbacks

drag_and_drop_v2/public/js/drag_and_drop.js

@@ -293,7 +293,7 @@ function DragAndDropBlock(runtime, element) {
                         content: str
                     });
 
-                    _fn.$popup.find(".popup-content").text(str);
+                    _fn.$popup.find(".popup-content").html(str);
                     return _fn.$popup.show();
                 }
             },

drag_and_drop_v2/templates/html/drag_and_drop.html

@@ -2,12 +2,12 @@
     {{ js_templates|safe }}
 
     <h2 class="problem-header">
-      {{ title }}
+      {{ title|safe }}
     </h2>
 
     <section class="problem" role="application">
         <div class="title1">Question</div>
-        <p>{{ question_text }}</p>
+        <p>{{ question_text|safe }}</p>
     </section>
 
     <section class="drag-container">

drag_and_drop_v2/templates/html/js_templates.html

 <script id="item-tpl" type="text/html">
     <li class="option" data-value="{{ id }}"
         style="width: {{ size.width }}; height: {{ size.height }}">
-        {{ displayName }}
+        {{{ displayName }}}
     </li>
 </script>
 
@@ -18,7 +18,7 @@
         left:{{ x }}px;
         width:{{ width }}px;
         height:{{ height }}px;">
-        <p>{{ title }}</p>
+        <p>{{{ title }}}</p>
     </div>
 </script>