Migrate from distutils to setuptools

[obriencj]

I am considering switching python-javatools to using setuptools rather than distutils for the next release. A preview of this change is in the setuptools branch, along with the beginning of some unittests -- facilitated by the change to setuptools.

setuptools is widely available, but I would like to see if any of the users of this project have reservations about such a change.

Please comment with your thoughts on the change.

[obriencj]

merged setuptools branch onto master. There wasn't any feedback, so...

Note that I've made it fall back to distutils if setuptools isn't present, but it may cause some warnings due to unused options to the setup function.