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
1) Any error conditions here that can happen for the zmq cleanup functions and that you should deal with or LOG?
2) Is there ipc files created in /tmp using this pattern?  Is zmq deleting these ipc files at exit or should you add file deletion of them?

Imagine a crashing scenario. the ipc file is corrupt.  What happens at next startup?