backup/restore: Add files from /etc/ipa/nssdb
    
    Add files from /etc/ipa/nssdb (IPA_NSSDB_DIR), which now used
    instead of /etc/pki/nssdb (NSS_DB_DIR).
    The old location is still supported.
    
    https://fedorahosted.org/freeipa/ticket/4597
    
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>