Preparations for simple communication

* Stub of topology registry
* Message loop inside Node class
* Modifications to zmq helpers
[CLEANUP] moved zmq-related functions to one directory
Nodes connect to each other in a single infrastructure

After each node is connected to all its neighbors, it is notified and it can start sending messages.

Apart from that:
* dedicated class for sending messages (transformed from topology class)
* extended zmq wrappers for support for inproc channels
* added a simple debug logger
* fixes build cmake file
* and a bento exception :)
Added an example application

Connect test establishes a defined topology and when it connects to all its neighbors signalises that fact. Just a simple application to test whether connection establishment does actually work.