Minimum viable product; healthchecks working

Healthchecks are now working

BUGS:
 - TCP only
 - Servers are globally identified by Id, and unique
 - When all servers fail, the VIP stops listening
Made a busy loop less busy

In the default case, when there's no healthcheck data, we should sleep for a few milliseconds.
Merge branch 'develop'

* develop:
  Made a busy loop less busy