Add CI for PRs

[Fleker]

Add CI support within GitHub to auto-respond to PRs

[mpoullet]

For this you can have a look at my 3 branches (all with badges in README.md too):

• Ubuntu 18.04 on AppVeyor: appveyor.yml
• Ubuntu 16.04 on CircleCI: .circleci/config.yml
• Ubuntu 14.04 on TravisCI: .travis.yml

Only someone with commit rights to the original repository can set CI up on these services though.

[Fleker]

Yeah I'm playing around with Google Cloud Build right now. Still trying to figure it out, but it could be pretty useful if it works.

[Fleker]

I'm getting it to pass now.