Add `CI` CLI

[azukaar]

Add a CLI to generate CI configuration.
The CI configuration generated should not detail steps and shouldn't need to be manually changed. They should point instead to scripts defined in a ci/.. folder.

# use provider-circleci to generate .circleci configuration
# will generate the ci/ folder if missing
g ci circleci 

The ci/ folder will contain the generic scripts like build.gs/test.gs/publish.gs

And each CI config will install GuPM and run the specific config that will always run build/test or publish

Should add the hook :

• generate-ci