to run rubocop locally and not to wait for HoundCI to bark at us.
The version is locked to 0.54 because this is the version HoundCI is using.
Using a newer version will not work as config changed from 0.54 to currently 0.59
and rubocop would complain with the old configuration.
thoughtbot uses the .rubocop.yml in thoughtbot/guides
as the orginizational config on Hound, so we inherit
from it so we can use the same config locally.
Fix#1195.
Christian Bruckmayer