post https://origin.myalerts.com/v1/users
Creates a new user. If the User already exists, the user will be updated. A new authorization token will be created on each call.
The response user id (item.id) is a MD5 hash of the first available value for the follow fields in this order: foreignId, email, phone. If none of these are provided, a random string is generated for the user id hash.
This would allow the user id to be determined before its creation, giving the flexibility of creating watchers in parallel or ahead of a watcher's corresponding user.