Replace LanguageCode with locale

The former is deprecated in Hugo.

themes/hermit/layouts/_default/baseof.html

@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html lang="{{.Site.LanguageCode}}">
+<html lang="{{.Site.Language.Locale}}">
 
 <head>
 	<meta charset="UTF-8">

themes/hermit/layouts/posts/rss.xml

@@ -3,7 +3,7 @@
 		<title>{{ if eq  .Title  .Site.Title }}{{ .Site.Title }}{{ else }}{{ with .Title }}{{.}} on {{ end }}{{ .Site.Title }}{{ end }}</title>
 		<link>{{ .Permalink }}</link>
 		<description>Recent content {{ if ne  .Title  .Site.Title }}{{ with .Title }}in {{.}} {{ end }}{{ end }}on {{ .Site.Title }}</description>
-		<generator>Hugo -- gohugo.io</generator>{{ with .Site.LanguageCode }}
+		<generator>Hugo -- gohugo.io</generator>{{ with .Site.Language.Locale }}
 		<language>{{.}}</language>{{end}}{{ with .Site.Params.Author.email }}
 		<managingEditor>{{.}}{{ with $.Site.Params.Author.name }} ({{.}}){{end}}</managingEditor>{{end}}{{ with .Site.Params.Author.email }}
 		<webMaster>{{.}}{{ with $.Site.Params.Author.name }} ({{.}}){{end}}</webMaster>{{end}}{{ with .Site.Copyright }}