RT Repo Structure, and tests repo

[steve.x.northover at oracle.com]

> They will be broken down into sub modules, so core would have javafx-beans, javafx-common, etc as sub modules. I guess by this logic concurrent could be a sub module of core as well... I'm happy to hear other proposals on how to break it up.
>

Concurrent needs graphics so it can't be in "core" unless "core" is 
redefined.

Steve