comment/todo re: directory creation
show staging directory (caskroom) in doctor

refs #6471
Bring the repo test back in sync with `.gitignore`.

This keeps the tests from failing, e. g. when developers use `rbenv` to run the 1.8-based tests.
Merge pull request #6493 from claui/fix-repo-layout-test

Bring the repo layout test back in sync with `.gitignore`
Upgrade Shortcat to 0.7.4
Merge pull request #6503 from crainiarc/shortcat

Upgrade Shortcat to 0.7.4
Merge pull request #6478 from rolandwalker/doctor_caskroom

print caskroom location in `brew cask doctor`