Add travis-ci support

Quoted comments outdated. See first response below.

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> https://github.com/opscode/test-kitchen#readme
> 
> This is currently mainly a chef issue, but will eventually be helpful for puppet as well. Just waiting for this to drop:
> 
> https://github.com/opscode/test-kitchen/pull/128
> 
> We should probably decide who'll donate the ec2/rackspace account. Shouldn't be a huge amount of bandwidth/hours. We'll want a separate one from any organizational ones we might already have kicking around.
>
> I would think we could add a "Testing sponsored by blah" mention in the README, unless you guys object. We can flip for it if multiple people are interested :)