bypass helm repo add failure with option --force-update (issue 74)

Presentation

Fixes #74 (closed) Add --force-update to helm repo add.

Checklist

• Documented:
  • README.md reflects any job, variable or whichever visible change
  • kicker.json reflects any job, variable or whichever visible change
• Tested & examplified:
  • (url to a project sample successfully proving the merge request fixes the issue)

No changes on Readme on kicker.json.

I tested it on my private repo. Before:

$ add_helm_repositories
[INFO] --- add repository myrepo: https://gitlab.com/api/v4/projects/.../packages/helm/stable (with user/password auth)
Error: repository name (myrepo) already exists, please specify a different name

After:

$ add_helm_repositories
[INFO] --- add repository myrepo: https://gitlab.com/api/v4/projects/.../packages/helm/stable (with user/password auth)
"myrepo" has been added to your repositories
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "myrepo" chart repository
Update Complete. ⎈Happy Helming!⎈