header: Do not generate RSS links if RSS disabled (Fix #318)

layouts/partials/header.html

@@ -64,8 +64,10 @@
     {{ end }}
   {{ end }}
 
+  {{ if or .Site.RSSLink .RSSLink }}
   <link rel="alternate" href="{{ .RSSLink | default .Site.RSSLink  }}" type="application/rss+xml" title="{{ .Site.Title }}">
   <link rel="feed" href="{{ .RSSLink | default .Site.RSSLink }}" type="application/rss+xml" title="{{ .Site.Title }}">
+  {{ end }}
 
   <link rel="icon" type="image/png" href="{{ "/img/icon.png" | relURL }}">
   <link rel="apple-touch-icon" type="image/png" href="{{ "/img/apple-touch-icon.png" | relURL }}">