Add "Hello, world!" web server
Add "Hello, world!" web server

We only speak HTTP/0.9, so depend on an nginx proxy on port 80 to allow
connections from recent-isa versions of Chrome.

google/CodeCity,NeilFraser/CodeCity,NeilFraser/CodeCity,NeilFraser/CodeCity,google/CodeCity,NeilFraser/CodeCity,google/CodeCity,google/CodeCity