Add open graph metadata to event#show

app/views/layouts/application.html.haml

@@ -5,6 +5,7 @@
     %title= content_for?(:title) ? yield(:title) : (ENV['OSEM_NAME'] || 'OSEM')
     %meta{:content => "", :name => "description"}
     %meta{:content => "", :name => "author"}
+    %meta= content_for?(:head) ? yield(:head) : ('')
     = stylesheet_link_tag "application", :media => "all"
     = javascript_include_tag "application"
 

app/views/proposal/show.html.haml

@@ -1,3 +1,10 @@
+- content_for :head do
+  %meta{ :property => 'og:title', :content => @conference.title }
+  %meta{ :property => 'og:image', :content => @conference.picture_url }
+  %meta{ :property => 'og:url', :content => conference_path(@conference.short_title) }
+  %meta{ :property => 'og:description', :content => @conference.description }
+  %meta{ :property => 'og:site_name', :content => (ENV['OSEM_NAME'] || 'OSEM') }
+
 .container
   .row
     .col-md-12.page-header