Web service that allows users to manage their client records for the CAPTCHA Service.

The following operations are supported. For a formal definition, please review the Service Description.

• ChangePassword
  Change the password for a specific client based on GUID.
• Register
  Create a new client, returning a client Model with a populated GUID and password.
• Update
  Update a specific client based on GUID.
• Get
  Get the ClientModel for a specific client based on GUID.