Resolve "Update Kubernetes version to install with rke"

Closes #7

See merge request openappstack/bootstrap!8

Smaller control image based on chatwork/helmfile

Closes #3

See merge request openappstack/bootstrap!11

Also:

- Add a .talismanrc file to ignore files beeing scanned by
  Talisman, a "tool that installs a hook to your repository
  to ensure that potential secrets or sensitive information
  do not leave the developer's workstation".
  See https://thoughtworks.github.io/talisman/
- Add .gitlab-ci.yml to build image from CI

Improve ci-bootstrap.py: Add argparser

See merge request openappstack/bootstrap!12

We now have:

  usage: ci-bootstrap.py [-h] (--create_droplet | --droplet_id ID) [--terminate]
                         [--verbose]

  Run bootstrap scriptto deploy Openappstack to a given node.

  optional arguments:
    -h, --help        show this help message and exit
    --create_droplet  Create droplet automatically
    --droplet_id ID   ID of droplet to deploy to
    --terminate       Terminate droplet after deploy
    --verbose         Be more verbose

Configure CI

Closes #10

See merge request openappstack/bootstrap!9

If you are using gitlint[1] to lint your commit
messages, this .gitlint file will ignore empty bodies.

[1] https://jorisroovers.github.io/gitlint/

Resolve "Destination directory /oas/control/local/rke does not exist"

Closes #12

See merge request openappstack/bootstrap!10

Resolve "Generate rke cluster configuration file from ansible"

Closes #5

See merge request openappstack/bootstrap!4

Resolve "Install apt-transport-https before installing any other package"

Closes #8

See merge request openappstack/bootstrap!6

Resolve "Segfault in control script"

Closes #11

See merge request openappstack/bootstrap!7