Use check_mode instead of always_run

[fabianfreyer]

always_run is being deprecated in ansible 2.4

[ypid]

This PR is incomplete as the check_mode was introduced in 2.2 and does not work with Ansible 2.1 which is the current minimum version for this role (ref: meta/main.yml).
Also note that the Ansible min version is also documented in:

• https://github.com/debops-contrib/ansible-checkmk_server/blob/master/docs/introduction.rst
• https://github.com/debops-contrib/ansible-checkmk_server/blob/master/README.md

(ansible-update-min-version could be used or a simple find | xargs sed combo.)

@ganto So far, I try to still support 2.1 for my roles but you can update the role to 2.2 min Ansible version if you like. I don’t see a problem with that.

[ganto]

@fabianfreyer Thanks for the PR. But currently the role defines version 2.1.1 as minimal supported Ansible version. Only to support a new variable name for the same feature which already exists now, I don't intend to raise that. That said, there is no hurry to move to check_mode yet.

Did you try to run the role with --check without issues but the dependency warnings? I can't remember if I even tried that yet.