SUDO: AD provider
    
    This patch adds the sudo target to the AD provider. The main reason is
    to cover different default settings in the LDAP and AD provider. E.g.
    the default for ldap_id_mapping is True in the AD provider and False
    in the LDAP provider. If ldap_id_mapping was not set explicitly in the
    config file both components worked with different setting.
    
    Fixes https://fedorahosted.org/sssd/ticket/2256
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>
    (cherry picked from commit 61804568ce5ede3b1a699cda17c033dd6c23f0e3)