use travis-ci.org for continuous integration

@rismoney

This branch builds cleanly on travis against my fork:
https://travis-ci.org/jumanjiman/puppet-chocolatey

* ruby 1.8.7 with both puppet 2.7 and 3.1
* ruby 1.9.3 with both puppet 2.7 and 3.1

travis-ci will run the unit tests on every push and every pull request
if you merge this branch and enable the github service hook from travis:
http://about.travis-ci.org/docs/user/getting-started/#Step-two%3A-Activate-GitHub-Service-Hook

You could then add a build badge to the readme:
http://about.travis-ci.org/docs/user/status-images/