Add support for Undo, Redo, Cut, Copy, Paste, and Select All from native menus

**NOTE: This pull request depends on adobe/brackets-shell#183**

These edit commands are handled differently than other menu items.

First, they are sent to the JavaScript code. If the JavaScript code does not handle the command, the shell calls the browser versions of these commands. This way, commands like Undo can be overridden by CodeMirror when an editor has focus, but fall through to the default implementation when a text field has focus.

This pull request also resets the name whenever a new menu or item is created. This makes the menus load correctly when reloading Brackets after changing the language.