Workflows should support uploading/downloading files as input types

There are several examples of workflow that would benefit from either providing a file to a user/group or collecting a file from a user/group.

Something like an Question / answer kind of thing. where who answers is decided at run time by the person asking the question.

An example might be ...

"Hey Chris... give me your public key" and I will add it to the server." 

Or

"Hey Application Owner team. Review this file and approve as is, or upload an updated file."
  ( The file could be anything from a Report of one or more groups  ( maybe in CSV form, or whatever ) to a graphic/visio drawing of some group math.