Add meta tags for Open Graph

Refers to issue #34

project/partials/_global/_head.hbs

@@ -12,6 +12,15 @@
   <link rel="shortcut icon" href="/assets/img/favicon.ico">
   <link rel="apple-touch-icon" href="/assets/img/apple-touch-icon-precomposed.png" sizes="152x152">
 
+  <meta property="og:title" content="Hive">
+  <meta property="og:type" content="website">
+  <meta property="og:description" content="A human-friendly digital currency wallet for multiple platforms">
+  <meta property="og:url" content="http://hivewallet.com">
+  <meta property="og:image" content="http://hivewallet.com/assets/img/opengraph-image.jpg">
+  <meta property="og:image:type" content="image/jpeg">
+  <meta property="og:image:width" content="1200">
+  <meta property="og:image:height" content="630">
+
   {{! no-js script for superfast fallbacks }}
   <script>
     document.documentElement.className = document.documentElement.className.replace(/(\s|^)no-js(\s|$)/, '$1' + 'js' + '$2');