RedMine Mirror Source

* Bundle the rubytree gem
* Patched RubyTree's TreeNode to add some additional methods.
* Converted the menu rendering to walk the Tree of MenuItems to render
each item
* Added a menu option for :parent_menu to make this menu a child of the parent
* Added a bunch of tests
* Made MenuItem a subclass of Tree::TreeNode in order to use it's methods
directly
* Changed the exceptions in MenuItem#new to be ArgumentErrors instead of the
generic RuntimeError

#4250