P.S. to above : Progress M-29M is pulled forward from an originally planned launch date of April 2016 (!).
The reason it can be ready that soon is because it was originally meant to stand ready as an operational backup in case something went wrong with the new Progress MS model. The current plan is now to replace M-26M with M-29M in September in order to have a Progress docked until up to March 2016 even if MS-1 has problems - Progress MS-2 is planned to launch in February. M-28M, originally slated for that replacement, won't last that far since it now launches in July.
Progress MS updates the automatic approach and navigation systems. Has been tested previously by M-21M, but in one of multiple dockings and redockings the automatic approach entered a safe mode and had to be overridden with crew on ISS manually docking her. Not that much of a problem (they have to manually berth Dragon, Cygnus and HTV every time), but something better to plan around.
Progress of course being important in this regard primarily since unlike everything else visiting it provides stationkeeping for ISS through its own thrusters and by delivering propellant to Zvezda.