Add optional title and class to menu items.

layouts/partials/header.html

@@ -9,8 +9,8 @@
     {{- $curr := . }}
     {{- range .Site.Menus.main }}
     {{- if .URL }}
-    <li>
-      <a href="{{ .URL }}">{{ .Name }}</a>
+    <li{{ with .Params.class }} class="{{ . }}"{{ end }}>
+      <a href="{{ .URL }}"{{ with .Title }} title="{{ . }}"{{ end }}>{{ .Name }}</a>
     </li>
     {{- else }}
     {{ .Name }}