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
Please add comments to this code. Each method should have a block comment.
Also a short writeup at the beginning of the file on the theory of how this queue works would be very helpful.