GitLab

Add playbook role to install or use CI with umap.

I discovered that CI runners could be manually activated for multiple
projects. It means I don't need to add a config section for each runner,
and can instead have a global one.

Playbook to use with ./chi-appliance configure to setup a CI
infrastructure on top of Chameleon nodes.

This playbook:
 - installs gitlab-runner
 - adds role to install or run ci on aml

I'm reluctant to add CI tokens in plaintext inside the infra repo.
Instead, ansible-vault is used to keep them encrypted.