Log Message:
Update ruby-celluloid-extras to 0.20.5.

0.20.5 (2015-09-30)
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* Resumed updating changelog.
* Revamped test suite, using shared RSpec configuration layer provided by \ 
Celluloid itself.
* Updated gem dependencies provided by Celluloid::Sync... extraneous gems \ 
removed, or marked as development dependencies.