add more stuff to Mac OS X package

First, I added a README (well, really, JES Information) file that
explains how to deal with Gatekeeper, missing Java, and other common
OS X issues.

Since that required a folder anyway, I decided to go ahead and include
the copyright file and the demos, like we do with the other packages.
properly default UI mode to "Beginner"

Because of a typo in JESConfig, the mode was defaulting to "Normal."
This is not actually a mode. It mostly worked the same as Beginner
mode, until you opened the Options dialog, at which point it would
flip to Expert mode.
actually gzip Linux .tar.gz file

Ant's default is to not gzip .tar files. Which makes sense, but I
skipped that section of the docs. So I was creating .tar.gz files that
weren't actually .gz'ed. :-/
don't put whole filename in title bar, just basename

I'm not very good at recognizing the effects of my changes.