Removed channel at_exit handler.
Removed channel at_exit handler.

lucasallan/concurrent-ruby,ferdinandrosario/concurrent-ruby,lucasallan/concurrent-ruby,lucasallan/concurrent-ruby,MadBomber/concurrent-ruby,hobodave/concurrent-ruby,ferdinandrosario/concurrent-ruby,ferdinandrosario/concurrent-ruby,ferdinandrosario/concurrent-ruby,lucasallan/concurrent-ruby,lucasallan/concurrent-ruby,MadBomber/concurrent-ruby,hobodave/concurrent-ruby,hobodave/concurrent-ruby,MadBomber/concurrent-ruby,hobodave/concurrent-ruby,MadBomber/concurrent-ruby