Add configuration for automated testing

Example pull request to show build status
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Add configuration for testing on travis-ci.org. Travis is a service that
automatically builds and tests code hosted on Github, allowing for
easy notification if any tests start breaking.

A guid is available at http://docs.travis-ci.com/user/getting-started/,
in short you register at travis-ci.org with your Github account then
select which repositories you'd like to have automatically tested. Tests
will be run whenever a new commit is added to the repository, as well as
whenever someone makes a pull request.