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

[msabramo]

This adds support for testing with tox.

Sample run:

marca@marca-mac:~/dev/git-repos/terrarium$ tox
...
  py25: commands succeeded
  py26: commands succeeded
  py27: commands succeeded
ERROR:   pypy: commands failed

Note: I know that you have Travis CI set up which I also love. I think it's handy to have both Travis CI and tox set up -- the reason is that tox lets developers test their changes locally across multiple Pythons without having to check in or push their changes. Thus, I find Tox super handy for working on Python 3 compatibility, because you can keep iterating on making changes and testing with Tox.

As for the pypy failure, there only seems to be one test failure, so I thought it might be easy to fix. I filed it as issue #39.

Note that you can run a single test more quickly like this:

tox -e pypy -- tests.tests:TestTerrarium.test_install_storage_dir_archive_extracted

[msabramo]

Any interest in this?

[winhamwr]

Hi Marc,

Thanks for the reminder, and sorry about the lack of response. I'm not speaking for @kylegibson, but from my perspective, I'm +1 on having a working tox setup.

One concern I have is the duplication between the tox.ini and the .travis.yml files. Ideally, it would be closer to the way https://github.com/PolicyStat/jobtastic handles things, with the .travis.yml calling tox. Does that make sense?

-Wes

[kylegibson]

Thanks for this pull request!