Update to Python 3.
Merge pull request #4: Python 3 compatibility

Pull request #4 on GitHub:
  https://github.com/xolox/python-coloredlogs/pull/4
Move demo code to separate module
Start using travis-ci.org (so I don't accidentally drop Python 3.x compatibility)

See also pull request #4 on GitHub:
  https://github.com/xolox/python-coloredlogs/pull/4
Bug fix for coloredlogs.demo module