R1:f8431bbfeed0

Make Aphlict client somewhat more approachable

Summary: Provide a reasonable JS API for the Aphlict client. Provide an example behavior to invoke it.

Test Plan:
Ran "aphlict_server.js" with:

$ sudo node aphlict_server.js

Loaded /aphlict/. Opened console. Got "hello" from the server every second.

Got reasonable errors with the server not present ("Security exception", but this is because it can't connect to port 843 to access the policy server).

Reviewers: ddfisher, keebuhm, allenjohnashton, btrahan…