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
If you have the same return type codes for your files then I would just add a very simple header file that just contains the return type ```enum class`` values.  Easy to include. Easy to read.