Add initial cred-prov support for change password scenario.
 - Only cred-prov code, no plugins yet.
 - Works by returning S_FALSE from GetSerialization so that Windows never
   processes the change.  Plugins will execute the change and GetSerialization
   will provide an appropriate message to the user.
Add password change pipe message.
Begin change password support in config.
 - New interface IPluginChangePassword
Configuration support for change password.
Change password support.
  - Change in parameters of IPluginChangePassword interface