actix-rt: v2.0.0-beta.1

Added

• Add System::attach_to_tokio method. [#173]

Changed

• Update tokio dependency to 1.0. #236
• Rename time module delay_for to sleep, delay_until to sleep_until, Delay to Sleep
  to stay aligned with Tokio's naming. #236
• Remove 'static lifetime requirement for Runtime::block_on and SystemRunner::block_on.
  • These methods now accept &self when calling. #236
• Remove 'static lifetime requirement for System::run and Builder::run. #236
• Arbiter::spawn now panics when System is not in scope. #207

Fixed

• Fix work load issue by removing PENDING thread local. #207