make CI builds and releases from travis-ci instead of jenkins

This request is to move building and releasing to travis ci so we can remove jenkins.  This also means we don't have sbt-release doing those annoying commits every time we release.  For now the changelog maybe broken but I will fix that later once we have some more history.

To do a build just get your changes into github and you'll get an email telling you it ran successfully or not.  If you want to do a release, tag the code with the version e.g. ```git tag -a v1.9 -m "version 1.9 shipped"``` and then push the tag to master e.g. ```git push origin v1.9```

@philwills please could you just check this looks vaguely sensible if you get a chance? =)