If you need to use something other than language: julia on travis, you can
check the couple of steps that get run for that by looking at the log of some
other repository that is using language: julia. For linux it's just a matter of
downloading and extracting the right tarball. On osx there are a few more steps
to mount the dmg image. I did write a script that would do these steps for you
but haven't been maintaining it or checking that it still works since we got
language: julia support incorporated on travis.
