Generic setup.py

I put all package-specific stuff inside a new module called `meta.py` and improved `setup.py`.

Now `setup.py` can be copied to any `localflavor` package, the only thing you need to adjust is the `meta.py` file.

I wasn't sure how to run the test suite, therefore this PR is untested. In case someone knows how to do that, I'd welcome the instructions.