add a button for creating portal when crowi-plus layout

lib/views/crowi-plus/widget/header.html

@@ -50,6 +50,13 @@
       </ul>
       {% endif %}
 
+      {% if not page and not isUserPageList(path) and !isTrashPage() %}
+      <div class="portal-form-button">
+        <button class="btn btn-primary" id="create-portal-button">Create Portal</button>
+        <p class="help-block"><a href="#" data-target="#help-portal" data-toggle="modal"><i class="fa fa-question-circle"></i> What is Portal?</a></p>
+      </div>
+      {% endif %}
+
     </div>
 
   </header>