Merge pull request #1805 from avalancheau/fix-activerecord-retry-on-restart

Prevent exceptions caused by Sidekiq::Shutdown from causing jobs to be retried
Never include modules if `.remove_delay` was called
Merge pull request #1778 from hundredwatt/optional_extension_loading

Optional extension loading
Climb cause chain to determine if exception is due to Sidekiq::Shutdown.