Call sign-up API endpoint from front-end

[reid-moffat]

Add a sign-up form to the front-end that:

• Has a button to submit that calls the createAccount API endpoint
• If the endpoint returns a success response, put some text on the screen telling them to confirm their email. Also have a sign-in button there so once they confirm their email they can sign in
• If the sign up failed, display an error message (either the email is in use, or some server error)