Many changes, including the removal of the Discovery projects from the solution.

Health modules now perform discovery operations. Ping Pong is now via a pub-sub
model. Slaves subscribe to the publisher after seeing a broadcast beacon from
which they get the address to subscribe to.

This means that slaves now have a constant connection to the master instead of
new connections being set up and torn down for each ping to each slave. The
REQ-REP model has it's advantages and would probably be better on a dispersed
grid, but as this is being built with a LAN grid in mind, the PUB-SUB model
seems like a better approach.