Remove duplicate OpenStruct monkey patch for specs
Remove unused rspec :focus metadata configuration

I actually remember that being kinda dangerous
from app development. If you happen to forget to
remove a :focus flag, only the focused tests will
be run.

During library development, I found myself simply
running the specs in question explicitly, using
something like:

  bundle exec rspec -cfs spec/file/path
Dry up spec helpers and use one configured DM_ENV