Implement distributed multi-master concept

[matt-attack]

Have nodes start up in interactive discovery mode (or have option to force to a particular master or disable this completely) then they will pick the nearest master if there is one. Otherwise continue in discovery mode.

If a node has a master it will query it for topic discovery and advertisement. This should greatly reduce non-data traffic and make the system actually scalable.

The masters should be able to discover and talk among themselves to sync topics between them.

[matt-attack]

The key priority with this is to make the networking complexity not scale with the number of topics or nodes as much as possible.

After a node starts up, it should only ping the master with periodic heartbeats. If the number of subscribers and publishers change, then it should notify the master. It shouldn't have to heartbeat per topic.

Topics with no subscribers should impose no bandwidth cost past initialization/destruction.