Allow parsoid to be easily deployed to appfog.

For new contributors or third-party users, appfog.com can be an easy
way to deploy a parsoid instance.  To support this use, we:

* Bind server to proper port for AppFog deployment
* Add 'npm start' command (AppFog uses the 'start' script to figure out
  how to run our app.)
* Add a manifest.yml describing parsoid.

Change-Id: Ieebd9b5c937a2b0a8e9d43e071acf346bf24b6c6
Merge "Allow parsoid to be easily deployed to appfog."