SGW-04: Enable gateway users to transfer files to or from a community resource

Executive Summary: 
A science gateway developer needs to enable gateway users to transfer files between a community resource and the gateway user’s local system without passing through the gateway host. These gateway users aren’t members of the gateway’s community project and don’t have access to the gateway’s allocation on the resource. The files and storage on the resource are owned by the gateway.
User Importance Summary: 
Some science gateways produce data that is big enough that the gateway's users will need to move it directly from the community resource to their own system(s) without using the gateway server as an intermediary. Ordinarily, gateway users aren't allowed to interact with community resources directly. A secure mechanism is needed to allow it in very specific, very limited circumstances.
Target Communities and Sizes: 
Science gateway developers - 100 < N < 1,000 Application developers - 100 < N < 1,000 Science gateway users -100,000 < N < 1,000,000