Fix Atom IDs to always be a URI

layouts/_default/list.atom.xml

@@ -21,7 +21,7 @@
 {{ end }}
 
 {{ if $page.Params.id }}
-    {{ $id = $page.Params.id }}
+    {{ $id = printf "%s?id=%v" (urls.JoinPath site.BaseURL "/") $page.Params.id }}
 {{ else if not $page.Date.IsZero }}
     {{ $id = printf "tag:%s,%s:%s" (urls.Parse site.BaseURL).Host ($page.Date.Format "2006-01-02") ($page.Date.Format $format) }}
 {{ else }}
@@ -140,7 +140,7 @@
             {{ end }}
 
             {{ if .Params.id }}
-                {{ $id = .Params.id }}
+                {{ $id = printf "%s?id=%v" (urls.JoinPath site.BaseURL "/") .Params.id }}
             {{ else if not .Date.IsZero }}
                 {{ $id = printf "tag:%s,%s:%s" (urls.Parse site.BaseURL).Host (.Date.Format "2006-01-02") (.Date.Format $format) }}
             {{ else }}