To create a new user
13. Click on POST /signUp button,
14. Click the Try it out button. The "User info for signUp" fields should show up.
15. Click the Edit button. The field should now become editable.
16. Fill out the requested fields, ie: first name, last name, email, password.
17. Click the blue Execute button.
18. If successful, you should receive an HTTP 200 response back with JSON data. If there was a form error, you should receive an HTTP 4XX response back with an appropriate error message.