Refactor gitkraken role

Closes #17

See merge request !24

The current gitkraken role is either insecure, outdated and overly
complicated.

This patch moves GitKraken to a flathub based setup that is easy to use
and can be upgraded easily.

Fixes: #17

since current firmware fix is available

Fix some minor issues with default-tooling

See merge request !23

[ci skip]

Fix/comparsion

See merge request !22

There is native flathub support for Ansible 2.6 so we should use it.

As it's already on Fedora, we don't need a legacy mode.

Since we switched to https://octa.sh we can't use Travis-ci anymore. We
should use gitlab-ci now.

- Removing Gitkraken because of missing upgrade repository
- Removing Keybase because of missing use-cases

Add tests for Fedora 28

We know what we do here and we do it intentional. It shouldn't cause a
warning here.

When running a commend by default there is always "changed" returned
which makes the playbook no longer idempotent. This change removed the
need of the command and this way provides this idempotence again.

RPM fusion published an updated version of their repo package in their
repo but serve the old one by URL. So it was up- and downgraded on every
run

Debian needs aptitude to successfully update packages. So we should
provide it…

As flatup updated their repository path we need to update our flathub
file for future working.