Simple SDK early sketch: objects for note, notebook, resource. Session object that does auth and owns functionality.
- Note allows "adding resource attachments" in a similar way to email compose. These are appended to the end of the ENML.
- Plaintext notes get the recommended div and br markup applied to them when uploaded.
- Updating existing notes is supported via return GUID on upload success. No good auto handling of overwrite confirm or overwrite-or-create.
- No freebie support for notebook creation yet. Not sure what the right flow for this should be. Handling tags and notebooks simply but without
  doing anything dumb behind the scenes is tricky.