Replace ok with circle for boolean icon

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/helpers/icons_helper.rb

 module IconsHelper
   def boolean_to_icon(value)
     if value.to_s == "true"
-      content_tag :i, nil, class: 'icon-ok cgreen'
+      content_tag :i, nil, class: 'icon-circle cgreen'
     else
       content_tag :i, nil, class: 'icon-off clgray'
     end