4139: Add environment configuration knobs for Node Manager tests.

These are settings I've fiddled with regularly over the course of
development, and now it looks like we're going to need to fiddle them
some more to accommodate Jenkins.  I'm exposing them as environment
variables so I can stop messing with the code appropriately.
Refs #4139.
4139: Add *.egg to Node Manager's .gitignore.

`python setup.py test` will automatically download dependencies to the
source directory if you don't already have them available in your
environment.  Refs #2881, #4139.
4139: Add README to Node Manager.

Refs #4139.