file io

- We still need to come up with a naming metaphor for this!
- it is a pipeline communication to stream a file from a server to a client.
- It follows a model similar to: http://zguide.zeromq.org/c:fileio3
I would change the logic here as well so that you capture the tmeout scenario first and then if its not timing out then you handle the normal case.... and FileRecv::Stream::CONTINUE will be then the default return. 

Otherwise static c++ analyzers will complain regarding possible lack of return values (surprised your compiler doesn't)