Investigate alternative CI systems

[dannys42]

Context and Description

All Kitura repos currently rely on travis.org / travis.com. TravisCI has retired travis.org. Under the new system in travis.com, we're allocated credits in 25k increments. Given the number of repositories and build variants, this can easily run out in a month. Once this happens, builds silently stop and an email must be sent to travis to request more credits. While they are generally responsive, this is quite inconvenient.

There are other CI systems out there, but unfortunately most require payment (including github). As Kitura is not a for-profit project, we do not have the funds to pay for CI infrastructure.

One CI system that appears to still be free for OSS projects is Cirrus CI. It would be good to investigate this as an alternative.