tox: explicitly test with Python 3.2 an 3.3
tox: test with Python 3.4

No code change needed.
tox: add support for Python 2.6

The OrderedDict class was added to the stdlib in Python 2.7. There is
a drop-in replacement on PyPI, but this does not work for Python 3, so
we still try importing the stdlib collections module first.
README: document supported Python versions
setup: don't rely on setuptools

We actually don't need setuptools for anything substantial so we can
just use the stdlib distutils instead. This fixes a build error when
pip (and thus setuptools) isn't installed in a LXC container.
Merge pull request #33 from mgeisler/tox-more-python-vers

tox: test more python versions
zvsh: don't nuke working dirs when saving rt files

If the user specifies a save dir for the runtime files (manifest,
nvram, etc.), don't nuke the entire directory! The original intention of
this was to ensure that the runtime files do not overwrite existing
files, but this is a destructive approach (and could result in the some
serious damage to the user's system). When I first encountered this bug,
I lost an entire git clone directory; luckily it was backed up a remote
repo, but I hope the risk here is clear.

So instead of nuking the directory, this change simply checks if the
runtime files we expect to create (nvram.1, manifest.1, etc.) exist. If
any exist, we halt. Otherwise, we continue writing to the target save
directory, whether it is empty or not.

The behavior when no save dir is specified does not change; we still
will create and cleanup a tempdir in this case.
Merge pull request #37 from larsbutler/dont-nuke-working-dirs

zvsh: don't nuke working dirs when saving rt files