SGW-06: Estimate when a submitted job is likely to be finished

Executive Summary: 
A science gateway developer needs a way for his/her gateway to inform researchers when to expect their computation tasks will finish. (These tasks are being submitted to XSEDE resources where either the gateway operator or the researcher using the gateway has an allocation. Tasks will likely not begin immediately due to competing uses of the system and scheduling policies.)
User Importance Summary: 
Researchers using science gateways are likely not aware of the competition for computational resources on XSEDE or the delays this causes in running jobs. To help researchers work efficiently, gateways should give them a reasonable sense of when their tasks will complete.
Target Communities and Sizes: 
Science gateway developers - 100 < N < 1,000 Application developers - 100 < N < 1,000