Snapshots on each commit and less chatty pull request build status thanks to Travis CI

[Thomas Broyer]

Hi,

I have moved from BuildHive to Travis CI, and configured the latter to automatically deploy a snapshot when the build is green.

Pull requests will now be checked by Travis CI instead of BuildHive. Travis CI uses GitHub's build status API rather than the chatty comment (+ mail!) used by BuildHive.

I've kept the BuildHive build around for those relying on it to trigger downstream builds, but if you think it's better to just remove it altogether I'd gladly turn it off.