add "sign in", register, and "load example" in place of default user bar.

[7yl4r]

• sign in: existing users load saved models, custom layout, messages, progress, settings, etc. This information is loaded from the database into the client's js.
• register: redirect to new page wherein users can request an account. This form submission is most easily handled through google forms or the sending of an email which triggers a canned response.
• load example: choose an example config and saved model. These accounts and example models can be based on famous psychologists and well known models. They serve to showcase different configurations as well as help users view familiar models.