Patches to add support for tox and Travis CI tools to psycopg2

Tox (http://tox.testrun.org/) is a nice tool for testing a package against
multiple Python distributions. If you want to pull my 2 commits for adding
support for this, fetch from the "tox" branch at:

https://github.com/msabramo/psycopg2.git

The commits are:

[last: 30] marca(at)scml-marca:~/dev/git-repos/psycopg2$ PAGER=cat git log
devel..tox
commit 3c510cf768e0a32b916172abd01a4aea902ea542
Author: Marc Abramowitz <marc(at)marc-abramowitz(dot)com>
Date: Fri Jun 15 02:57:11 2012 -0700

Add .tox to .gitignore

commit 9e1e69003b1fa74d2e2ea62dda1bc8444b85d438
Author: Marc Abramowitz <marc(at)marc-abramowitz(dot)com>
Date: Fri Jun 15 02:56:44 2012 -0700

Add tox.ini for tox (http://tox.testrun.org/)

Travis CI (http://travis-ci.org/) is a hosted CI system "in the cloud". For
that, pull 1 commit from my "travis" branch:

[last: 1] marca(at)scml-marca:~/dev/git-repos/psycopg2$ PAGER=cat git log
devel..travis
commit 6bf2b1b465d573d7fabcc5c98870b13c4d5eaae1
Author: Marc Abramowitz <marc(at)marc-abramowitz(dot)com>
Date: Fri Jun 15 07:27:00 2012 -0700

Add .travis.yml for Travis CI (http://travis-ci.org/)

Cheers,
Marc