Update Hugo docs with the initialisms suggested by golint

In particular:

 * .Url → .URL (for node, menu and paginator)
 * .Site.BaseUrl → .Site.BaseURL
 * getJson → getJSON
 * getCsv → getCSV
 * safeHtml → safeHTML
 * safeCss → safeCSS
 * safeUrl → safeURL

Continued effort in fixing #959.

docs/layouts/partials/menu.html

@@ -16,12 +16,12 @@
             </a>
                 <ul class="sub{{if $currentNode.HasMenuCurrent "main" . }} open{{end}}">
                     {{ range .Children }}
-                    <li{{if $currentNode.IsMenuCurrent "main" . }} class="active"{{end}}><a href="{{.Url}}">{{ .Name }}</a> </li>
+                    <li{{if $currentNode.IsMenuCurrent "main" . }} class="active"{{end}}><a href="{{.URL}}">{{ .Name }}</a> </li>
                     {{ end }}
                 </ul>
               {{else}}
                 <li>
-                <a class="" href="{{.Url}}">
+                <a class="" href="{{.URL}}">
                     {{ .Pre }}
                     <!--<i class="icon_house_alt"></i>-->
                     <span>{{ .Name }}</span>