Add more descriptive error message

[maximiliankolb]

I have reworded the error message that is shown in Foreman if you try to run this job template on a managed hosts that does not have the "kernelcare" package installed.

cc @nadjaheitmann

[nadjaheitmann]

Tests are failing:
ArgumentError: wrong number of arguments (given 4, expected 1) /home/runner/work/foreman_kernel_care/foreman_kernel_care/vendor/bundle/ruby/2.5.0/gems/psych-5.1.0/lib/psych.rb:322:in 'safe_load' /opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/safe_yaml.rb:31:in 'safe_load'

Could this be related to usage of double quotes in single quotes? Or is this just random? @maccelf Do you mind restarting the rubocop test?

[maccelf]

@nadjaheitmann I am not sure about the error related to these changes. This error is related to installing dependencies via bundle

[nadjaheitmann]

Not sure either, the change looks very harmless. But we should try to figure out what happened or if this is just a hick up.

[nadjaheitmann]

Compared to the last successful bundle install run for rubocop tests, there is now psych 5.1.1, it was at psych 5.1.0 .

[nadjaheitmann]

#58 has the same error message for rubocop, so definitely unrelated. I think, we can try and fix rubocop in a separate PR.