Only load flag CSS if showing flag icons (#666)

layouts/partials/header.html

@@ -7,8 +7,9 @@
 <link rel="stylesheet" href="{{ "/css/layouts/main.css" | relURL }}"/>
 <link rel="stylesheet" href="{{ "/css/navigators/navbar.css" | relURL }}"/>
 <link rel="stylesheet" href="{{ "/css/plyr.css" | relURL }}"/>
+{{ if ne site.Params.showFlags false }}
 <link rel="stylesheet" href="{{ "/css/flag-icon.min.css" | relURL }}"/>
-
+{{ end }}
 <!--=================== fonts ==============================-->
 <link rel="stylesheet" href="{{ "/google-fonts/Mulish/mulish.css" | relURL }}"/>