setup.py: Add disutils-based packaging

setup.py: Add disutils-based packaging

Package catalyst in the usual manner for Python projects.  Now it is
ready for PyPI :).

I also expose the version string in catalyst.__version__ and the
maintainer string in catalyst.__maintainer__, since those are more
traditional locations.

I dropped official Python 2.6 support following:

  19:31 <@jmbsvicetto> I don't see a need to make catalyst
        incompatible with 2.6, but I think it's time we drop it as a
        "requirement". So feel free to do any changes that improve the
        code, even if they drop 2.6 compatibility

I kept the explicit indexes in the string formatting, since Python 2.6
doesn't support:

  '{}'.format(value)