Removed FileMQ support from libzre

The file transfer stuff was rather ugly and hacked into Zyre. It would be
better to do this on top of Zyre's messaging rather than beside it. It
also makes Zyre more complex than it needs to be.
Renamed main programs to not look like library modules
Merge pull request #109 from hintjens/master

Removed FileMQ support from libzre