Add a smoke test, running yard on the full yard source
Add a smoke test, running yard on the full yard source

As this will take a significant fraction of the running time of the
whole test suite (roughly 4x more than the rest), we isolate this
test in its own file.

Therefore, one can run the whole test suite as before with:

  bundler exec rake spec

Or the whole test suite except this smoke test:

  rspec --exclude-pattern spec/cli/yard_on_yard_spec.rb

lsegal/yard,thomthom/yard,thomthom/yard,lsegal/yard,thomthom/yard,lsegal/yard