'Add node' functionality. This includes

- Add jquery.hotkeys and fancytree.hotkeys to be able to signal when and
  where a node is to be added.
- Make edit_create in Jet::Role::Update actually work.
- Add validator and a dfv attributes to JRU so that the dfv can be
  easily modified. Default is still taken from the basetype.
  In the Jet::Engine::Config workflow, we add some columns to dfv's
  required dept.
Enums can be either hashrefs or plain scalars. Make it easier to see
which it is, and avoid error messages.