gitops init -- Add CLI command to set up a new cluster repo.

[jarekwg]

(moved this out of readme, zero prio to work on it atm though).

Add a command to create a template cluster repo (ala uptick-cluster) and give instructions to push it up and set up a webhook.

Developer experience should look something like:

pip install gitops
gitops init-repo
    -> Creates cluster repo (maybe with examples?)
    -> Explains or pushes repo up somewhere.
    -> Explains or sets up a webhook on that repo.
gitops init-secrets
    -> Either downloads secrets from AWS using awscli or
    -> Prompts for each secret individually.
gitops deploy-server
    -> helm upgrade gitops chart... (see tasks.py:deploy)