rubocop 0.27 is picky about the Berksfile

TelekomLabs-DCO-1.1-Signed-off-by: Edmund Haselwanter <me@ehaselwanter.com> (github: ehaselwanter)
Merge pull request #5 from ehaselwanter/rubocop-fixes

rubocop 0.27 is picky about the Berksfile