Improve OS menu (#1563)

* Remove reload options, new file/help menus, tools/log at bottom

* Further menus refactor: install handlers at template creation

* WIP: Further tune menus, add custom about window

* New About window, new help menu items, menu labels now i18n

* Default device name on registration is now computer hostname

The OS of the device makes sense for those of us testing across a lot of
different OSes. And maybe for a user with just one desktop device. But
most users with multiple desktop devices are using the same OS for both.

* About window: Only show window when content is ready

* Fix typo in app/menu.js

test/index.html

@@ -47,7 +47,6 @@
                 <button class='hamburger' alt='signal menu'></button>
                 <ul class='menu-list'>
                     <li class='showSettings'>{{ settings }}</li>
-                    <li class='show-debug-log'>{{ submitDebugLog }}</li>
                     <li class='restart-signal'>{{ restartSignal }}</li>
                 </ul>
               </div>