Add tox.ini

[carljm]

We should add a tox.ini to automatically test dzclient on multiple Python versions (and consider supporting 2.4 so Talos can use it).

[carljm]

This makes it easy to make sure we don't break compatibility with Python 2.5+.

I took a look at also adding 2.4 compat, but there are compatibility issues in oauth2 that I don't want to deal with here. Talos will be bundling copies of this stuff anyway, it'll make more sense to deal with that stuff there, since that's the only place I expect to be using this under 2.4 anyway.

[malini]

/me kicks github

I did not see this pull request nor get email notifications for any of your comments, so sorry for this CRAZY delay. I'm getting a bugzilla component for Datazilla, so we can get all patch reviews up there. It's much easier that way since notifications are much louder, and people can subscribe to the new bugzilla component.

[carljm]

No worries, I wasn't waiting on this - thanks for merging!