[] The API listens on PORT and accepts incoming HTTP request for POST, GET, PUT, DELETE and HEAD.
[] The API allows a client to connect, then create a new user, then edit and delete that user
[] The API allows a user to sign in which gives them a token that they can use for subsequent authentication requests.
[] The API allows the user to sign out
[] The API allows a signed-in user to use their token to create a new "check"
[] The API allows a signed-in user to edit or delete any of their checks
[] In the background, workers perform all the "checks" at the appropriate times, and send alerts to the users when a check changes its state from "up" to "down", or visa versa