Extract Ouranos specific config out to a separate config file so it can be override

[tlvu]

@huard: We now have a jenkins-private-config repo that can override the example file jcasc_extra_example/jenkins_extra.yaml.

That example is there so Jenkins has all the minimal config to start up so we can easily demo the features of this repo. I actually left the noreply@ouranos.ca in the example because that's not anything confidential and that email do not even exist for real.

This jenkins-config repo is now public.