A round of modernizations incl. rubocop & pidfile cleanup
Removing bundler version restriction

as it is not a common source of false-y positives, and pinning it is breaking CI atm
Reduce ruby version matrix a touch
Replacing custom pidfile cleanup with at_exit block

and removing the in-process test.  Best effort is best effort.
Tweaks to travis config now that we're green
One more rubocop autogen
Merge pull request #459 from resque/modernization-sweep

Modernization sweep