Add diff list to menu

Author: kevinsawicki

menus/git-diff.cson

@@ -6,6 +6,7 @@
       'submenu': [
         { 'label': 'Move to Next Diff', 'command': 'git-diff:move-to-next-diff' }
         { 'label': 'Move to Previous Diff', 'command': 'git-diff:move-to-previous-diff' }
+        { 'label': 'Toggle Diff List', 'command': 'git-diff:toggle-diff-list' }
       ]
     ]
   }