modified pyre so you need to start explicitly using the start() method

...This is needed to support adding

headers before we announce ourselves on the network. It is also needed for future gossip support.
- added self.beacon_socket container to PyreNode to keep the run method simple
- refactored the stop method so it won't fail if sockets aren't initialized
- updated the chat example to reflect the start addition
Fixed some api methods to check if peer exists