Add flattr meta tag

Signed-off-by: Harsh Shandilya <msfjarvis@gmail.com>

themes/hello-friend-ng/layouts/partials/head.html

@@ -5,6 +5,7 @@
 <meta name="description" content="{{ if .IsHome }}{{ .Site.Params.homeSubtitle }}{{ else }}{{ .Summary | plainify }}{{ end }}" />
 <meta name="keywords" content="{{ .Site.Params.keywords }}" />
 <meta name="robots" content="noodp" />
+<meta name="flattr:id" content="xj7zpw">
 <link rel="canonical" href="{{ .Permalink }}" />
 <script>
     if ('serviceWorker' in navigator) {