Remove duplicate private keyword
Use binstubs in runners when present.

Rails 4 makes extensive use of the bin/ directory for executables. We
should default to using that file if it is present, otherwise fall back
on the previous options.
Merge pull request #222 from felixclack/use-binstubs-in-runner

Use binstubs in runner
indent
Thanks Felix!
v0.13.3
make everything private
Merge branch 'master' of https://github.com/grosser/parallel_tests

Conflicts:
	lib/parallel_tests/grouper.rb