Allow absolute pid paths (for Capistrano)

[jbourassa]

The rake tasks forces sidekiq_pid to be relative to Rails.root.

    # must be relative to Rails.root. If this changes, you'll need to manually
    # stop the existing sidekiq process.
    set :sidekiq_pid,             ->{ "tmp/sidekiq.pid" }

This causes an issue when deploying with Capistrano: some tasks are executed before the symlinks are created, thus causing the file test ([-f path_to_pid ]) to fail when it shouldn't.

I will submit a fix shortly.

PS: Awesome gem. 1,000 open source points to the maintainer(s)!

[jbourassa]

Let me know what you think!

(The PR on my fork was a mistake, please disregard it)

[mperham]

Seems ok, thanks.