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
It's not of high priority but you might want to collapse the code duplication
```void*  FileRecvTests::SendThreadSendData(size_t number_of_sends, size_t amount_per_send, bool send_ending) {...}