In the discussion of Zola's Algorithm, Agent Sitwell specifically mentions Bruce Banner and Stephen Strange as persons of interest. Obviously Cap knows Bruce Banner, and (a good portion of) the fanbase knows who Stephen Strange is: the guy who eventually becomes Dr. Strange, Sorcerer Supreme. Soon after this, it was officially announced that there was a Dr. Strange movie in the works as part of Phase 3 of the Marvel Cinematic Universe.
Since the Dr. Strange movie will (presumably) take place after the events of Captain America: The Winter Soldier, the hero Dr. Strange, Sorcerer Supreme does not exist yet. And yet Agent Sitwell name-drops the guy right alongside one of Captain America's companions, like he's someone Captain America (or possibly The Falcon) should know by name.
Is there any reason why they should? Who is Stephen Strange before he becomes a superhero?