Failure on OSX

[shmul]

Hi,

Just tried to run version 1.0.0 on OSX (check-process.rb -p redis) and it immediately failed with
Check failed to run: undefined method 'exitstatus' for nil:NilClass, ["/Library/Ruby/Gems/2.0.0/gems/sensu-plugins-process-checks-1.0.0/bin/check-process.rb:205 ...

I simply added $CHILD_STATUS && to the check.

def on_cygwin?
    # #YELLOW
    `ps -W 2>&1`; $CHILD_STATUS && $CHILD_STATUS.exitstatus == 0 # rubocop:disable Semicolon
  end

Not really worth a pull request :)

Cheers,
Shmul

[thisisjaid]

Ran into same today, was going to do a PR with something a bit more complicated, but your fix seems adequate as I can't really imagine any instance in which you'd actually need to read that status if you're on OSX anyway. Thanks for posting it.