Move CI from GitLab to CircleCI

[jmaupetit]

Purpose

Historically, this project has been initiated using our own GitLab instance, hence, we designed a GitLab-CI-based continuous integration (CI) workflow. When we decided to open-source this project and move it to GitHub, we lost our CI. As it is a prerequisite for this project (for every project in fact), we need to improve and re-implement it.

Proposal

As we usually use CircleCI, let's stick to it for Arnold. We have the advantage that CircleCI and GitLab-CI philosophies are quite close. Therefor, we might thought that this will be an easy task, but it's not. The way we designed our original CI workflow is not sustainable for an open source project (the last step is a deployment to our OpenShift instance).

My first idea is to use a trashable MiniShift instance in our CI workflow, but this will be a really tricky part.

Dear contributors, I invite you to make proposals; nothing has been decided yet.

[cchaudier]

The project openshift-acme use the oc cluster up command to launch OpenShift on Travis.
I think we can try it on CircleCI.

[cchaudier]

For the OpenShift deploy I've create the Issue #48