Ticket 47595 - 47590: enhancements of lib389 (continuation)

Bug Description:
        - ability to create backup
        - Create agreement/index class in brooker
        + Fix Replica.add with 'role' of replica
        + enableReplication raise exception on error
        + add __str__ for RUV
        + support platform without SELinux

Fix Description:

Reviewed by:  Roberto Polli

http://fedorahosted.org/389/ticket/47595
http://fedorahosted.org/389/ticket/47590

Platforms tested: F19

Flag Day: no

Doc impact: no