sss_sifp: make it compatible with latest version of the infopipe Current version of infopipe leverage different interfaces and object paths which were not accessible through the simple ifp library. This patch changes the API, which is ok since it was never declared as a public library and beside deprecated openlmi there are no known users. We will use this in sssctl tool. Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>

sss_sifp: add shortcuts for common use cases https://fedorahosted.org/sssd/ticket/2254 Reviewed-by: Sumit Bose <sbose@redhat.com>

sss_sifp: add support for string dictionary https://fedorahosted.org/sssd/ticket/2254 Reviewed-by: Sumit Bose <sbose@redhat.com>

sss_sifp: introduce API https://fedorahosted.org/sssd/ticket/2254 Reviewed-by: Sumit Bose <sbose@redhat.com>