Ticket 47593 - Update plugin API for OTP plugin
    
    Description:  The upcoming OTP plugin from IPA needs a API update.  Some of the
                  password scheme functions need to be available in the plugin API.
    
    https://fedorahosted.org/389/ticket/47593
    
    Reviewed by: richm(Thanks!)
    (cherry picked from commit 6b83caf7167e74672c4b28e1958ddbcab7cfc2d8)