FEATURE: store tutorial progress and continue

[ShMcK]

Current plan for storing user progress and allowing continuing.

Unfortunately, local storage must be stored on editor rather than in client, as it does not exist within the editor browser.

A tutorial can be uniquely identified by its id and version, which should be sufficient to properly load it.

Proposed structure:
currentTutorial: { id: 'some-id', version: 'some-version' }
progress: { 'some-id@some-version': progressObject }

@jensen love to hear your thoughts on this one as well