Minor cleanups

Experimental synda release on conda. Only incorporates SDT components.

• 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.

• CDS variable event Added

• add 'info' action to 'synda certificate' command.
• all deletions now occurs synchronously (deferred mode is disabled).
• follow symlinks during 'synda remove' operation.
• new cleanup algo for 'synda remove' command (run faster).
• add full path support in 'local_path_drs_template' var.
• store stacktrace file in /tmp.
• fix permission in sys-pkg for /srv/synda/sdt folder (g+sw).

• add user personal env (SDT_USER_ENV).
• synda group can be used instead of sudo (system package).
• set specific version for pillow package.
• bugfixes.

• synda group can be used instead of sudo (system package).
• bugfixes.

• use search-api json format instead of xml.
• trigger end-of-transfer events in batch mode.
• add 'synda count' subcommand.
• add 'synda config' subcommand.
• add incremental mode for discovery operation.
• add dataset version consistency check.

• move hard-coded pipeline dependencies into configuration files.
• add credentials.conf file.
• add pipeline samples.
• bugfixes.

• support for lowmem machine.
• add 'url_replace' selection file parameter.
• add 'http_fallback' option (switch protocol on error).
• add 'default_listing_size' configuration option.
• add '-m' option to 'synda remove command'.
• add 'check' action for selection file.
• add 'check' action for file's variable.
• add new 'open' action.
• add 'default_path' option in sdt.conf.
• bugfixes and ergonomy improvement.