added og tags

_includes/themes/bootstrap-3/default.html

@@ -10,6 +10,10 @@
 
     <!-- Enable responsive viewport -->
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <meta property="og:url"                content="http://radicalnetworks.org" />
+    <meta property="og:title"              content="Radical Networks 2016" />
+    <meta property="og:description"        content="November 4-6, 2016 at Chemistry Creative, 315 Ten Eyck Street, Brooklyn NY" />
+    <meta property="og:image"              content="http://radicalnetworks.org/assets/themes/images/banner_fb2.jpg" />
 
     <!-- Bootstrap styles -->
     <link href="{{ ASSET_PATH }}bootstrap/css/bootstrap.min.css" rel="stylesheet">