Give `Accept-Language` div its own class (#659)

Fixes accidental assignment of "get-only" class to the
"Accept-Language" config option

app/templates/index.html

@@ -200,7 +200,7 @@
                             <input type="checkbox" name="get_only"
                                    id="config-get-only" {{ 'checked' if config.get_only else '' }}>
                         </div>
-                        <div class="config-div config-div-get-only">
+                        <div class="config-div config-div-accept-language">
                             <label for="config-accept-language">Set Accept-Language: </label>
                             <input type="checkbox" name="accept_language"
                                    id="config-accept-language" {{ 'checked' if config.accept_language else '' }}>