Aphlict, simple notification server

Summary:
This is purely a prototype at the moment, but the basic functionality sort of
works.

I'm not sure how far I want to go with this but I think we might be able to get
somewhere without it being gross.

The idea here is to build a notification server WITHOUT using Comet, since Comet
is extremely difficult and complicated.

Instead, I use Flash on the client. LocalConnection allows flash instances to
talk to each other and connect() can be used as a locking primitive. This allows
all the instances to elect a master instance in a race-safe way. The master is
responsible for opening a single connnection to the server.

On the server, I use Node.js since PHP is pretty unsuitable for this task.

See Github Issue #3: https://github.com/facebook/phabricator/issues/3

One thing I need to figure out next is if I can reasonably do SSL/TSL over Flash
(it looks like I can, in theory, with the as3crypto library) or if the server
needs to just send down version information and trigger a separate Ajax call on
the client.

Test Plan:
Created a client pool and connected it to the server, with election and failover
apparently working correctly.

Reviewed By: aran
Reviewers: Girish, aran, jungejason, tuomaspelkonen, davidrecordon
Commenters: Girish, davidrecordon
CC: aran, epriestley, Girish, davidrecordon
Differential Revision: 284