Merge pull request #8 from ardeois/master

Bug Fix: #7: Device serialization for 'height' field on Ubersmith 3.0.0 fails
rev to 0.2.0, upload sdist to pypi, and update install in readme
Clean time field on invoive_payments call
Add travis config and extend tox to cover python 2.6.
trying to get travis to start building
revert that
add travis build status to readme
fix tests in python 2.6
Merge branch 'master' of github.com:jasonkeene/python-ubersmith