Menus don't show accurate shortcuts if any shortcuts added/removed directly via KeyBindingManager

[peterflynn]

Add this code to an extension, or at the bottom of Menus.init():

    // Bug 1
    KeyBindingManager.addBinding(Commands.FILE_OPEN_FOLDER, "Ctrl-Alt-O");

    // Bug 2
    KeyBindingManager.removeBinding("Ctrl-Q");

    // Bug 3
    var MY_COMMAND_ID = "helloworld.sayhello";
    CommandManager.register("Hello World", MY_COMMAND_ID, function () {
        window.alert("Hello, world!");
    });

    KeyBindingManager.addBinding(MY_COMMAND_ID, "Ctrl-L");

    var menu = Menus.getMenu(Menus.AppMenuBar.FILE_MENU);
    menu.addMenuItem("menu-helloworld-sayhello", MY_COMMAND_ID);

Result:

1. File > Open Folder does not show any keyboard shortcut (even though pressing the shortcut works)
2. File > Quit still shows "Ctrl+Q" as its shortcut (even though pressing the shortcut does nothing)
3. File > Hello World does not show any keyboard shortcut (even though pressing the shortcut works)

To fix (1) & (2), KeyBindingManager needs to dispatch change events and Menus needs to listen to them and update the menu item UI.

To fix (3), KeyBindingManager needs to expose an API for getting the bindings for a specific Command and that Menus needs to call that API when initially constructing the menu item UI, rather than assuming that the only bindings that exist are those that were passed directly to it as args.

[jasonsanjose]

@peterflynn @tvoliter If you guys don't mind, I can look at this one while Ty is out sick.

[peterflynn]

Confirmed fixed