Fix #8. Support Python 2.6
Reimplement check_output, for readability.
Make argparse an optional dependency (and avoid pinning in a library).
Add Travis integration.
Add cram dependency (for tests).
Add build status PNG.
Remove Python 3.0 support.
Use Python version that is active in the current venv (on Travis).
Remove Python 3.3 (cram does not support it).
Merge branch 'mbraak-python2.6'
Add with statement support for Python 2.5.
Rewrite tests smartly, to support all Python environments, including Travis'.
Install argparse on all envs.

Older Python envs require it, on newer envs it does not harm.
Fix Python 2.6 compatibility.
Add json as a pre-py26 requirement.
Screw Python 2.5 compat.</frustration>
Add Trove classifiers for supported Python versions.
Declare that Python 3 is not supported yet.
Add tox (for testing in multiple envs locally).
Update README.