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
Should I read this function (```RecvThreadGetFileDie```) as:
ReceiveThread  --- Get File --- Fail and Die?

I wouldn't mind function name change to ```RecvThreadGetFileAndDie```.   No need to save number of characters. Strive for clarity.