* Refactored some of validator decorator to use clearer variable names internally.
* Validator decorator now supports treating arguments with default values as optional.
* controller.Notebooks.default() takes an optional note_id argument.
* controller.Notebooks.contents() takes an optional note_id argument.
* Wiki.js now makes use of these new controller APIs.
* Editor.js now takes a notebook_id argument to its constructor so it can properly make links.