sdt/3.9

• Datasets attributes are now available to local_path_drs_template impl.
• Added gridftp_opt option in sdt.conf.
• Checksum computation time excluded from download time metrics.
• Pillow lib version is set.
• Enabled supplementary group support if available.
• Added ubuntu 16 support.
• Interactive messages improved.
• Certificate is now renewed at each scheduler cycle.
• CDS variable event added.
• Various bug fixes.
• Documentation updated.