Add main and admin servlets, taken from finatra example.

I wonder just how long it would take before all threads saw the update. I suspect it's of little consequence, for this data at least.

Every host in the system serves this information. Since the nodes (peers) in the system do not get updates at the same time, so the system is designed to handle some nodes having it slightly out of sync. Because of that, I expect that it's alright if some threads are out of sync.