Make enabled an optional attribute.
Merge branch 'master' of github.com:kolemannix/edu-

Conflicts:
	resources/public/js/input/directive.js
Merge branch 'master' of github.com:kolemannix/edu-
Merge branch 'master' of github.com:kolemannix/edu-
Merge branch 'master' of github.com:kolemannix/edu-
Push-state on item / category added.
Frontend now loads and saves to the backend.

Huzzah!
Persistance!

Change models.js creation to remove weird behavior when entire model is replaced.
Don't render graph when app state empty.
Confirm before navigation with unsaved changes

Keep track of changes in sessionService and intercept window.onbeforeunload events.