app/views/vocal/shared/_facebook_open_graph.html.erb
<meta property="og:title" content="<%= @meta.title %>"/>
<meta property="og:type" content="website"/>
<meta property="og:url" content="<%= request.original_url %>"/>
<% if Vocal.config.meta.has_key?(:image_url) %>
<meta property="og:image" content="<%= Vocal.config.meta.image_url %>"/>
<% end %>
<meta property="og:site_name" content="<%= Vocal.config.meta.title %>"/>