The navigation through a bunch of config files, all with just a few
lines in it is cumbersome. This change moves all the configuration into
a centralized `config.ini` that way it's easier for me to get a quick
overview of the setup. The `config.ini` acts as another inventory and is
therefore references as such by the ansible.cfg. The `inventory.ini`
(which is generated by terraform in the provisioning-step) is not
affected by this change.
