Insert menu item before "Bring All to Front"

There's a lot of real estate between that ⇧⌘2 and ⇧⌘9.

For example, Attica[1] uses ⇧⌘8, and because of Xcode plug-in load
order, it's inserted after Alcatraz, yielding a menu that looks like
this:

  Documentation and API Reference  ⇧⌘0
  Welcome to Xcode                 ⇧⌘1
  Organizer                        ⇧⌘2
  Package Manager                  ⇧⌘9
  Snippet Editor                   ⇧⌘8

If we insert the item before the section's separator item, we can cure
my mild case of OCD.

[1]: https://github.com/kattrali/attica

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Merge pull request #145 from stephencelis/menu-insertion-order

Insert menu item before "Bring All to Front"