Integrate with Travis and Coveralls

[Travis CI](https://travis-ci.org/) is a continuous integration service that is free for open source projects. [Coveralls](https://coveralls.io/) is a test coverage tracking service that is also free for open source projects. This pull request adds support for integrating with these two services.

~~The pull request also disables the tests for the Google Translate module, which appears to be broken based on my testing. I have disabled those tests in a separate commit, so I can easily remove that commit from this pull request if the commit turns out to be working.~~ See 6767987

This should address https://github.com/embolalia/willie/issues/371.