setup.py for jobTree

This setup.py script enables installation with `./setup.py install`. Doing a `./setup.py install --user` will put the Python modules in the user's python module directory, and the executable scripts in the user's Python script directory (probably ~/.local/bin). You ought to be able to uninstall with `pip uninstall jobTree`.

Also, this pull request makes the scriptTree interface classes new-style classes. All tests still pass on hgwdev.