python: Add setuptools for Python lib for PyPI.

python: Add setuptools for Python lib for PyPI.

This adds very basic support for setuptools so that the OVS Python
lib can be added to PyPI.

This currently uses the Open vSwitch version number and the
generated dirs.py, though there is no real reason to tie the
Python libraries releases or version numbers to the main project's.

Signed-off-by: Terry Wilson <twilson@redhat.com>
Acked-by: Russell Bryant <rbryant@redhat.com>
Acked-by: Kyle Mestery <mestery@mestery.com>
[blp@nicira.com adjusted automake.mk]
Signed-off-by: Ben Pfaff <blp@nicira.com>