Add libsss_sudo for sudo + fedora/sssd container
    
    Central management of the sudo rules could not be used with
    a container (fedora/sssd) because the Fedora Atomic Host ostree
    did not contain the necessary library.
    
      atomic$ sudo id
      sudo: unable to load /usr/lib64/libsss_sudo.so: /usr/lib64/libsss_sudo.so:
            cannot open shared object file: No such file or directory
      sudo: unable to initialize SSS source. Is SSSD installed on your machine?
    
    This change is related to adding sssd-client on atomic host.
    5aef550246201bf0b9df976cd9c079ba5536b88c
    See:
    - https://lists.projectatomic.io/projectatomic-archives/atomic-devel/2015-October/msg00055.html