Celluloid::Method should respond to Method methods

When you use Celluloid Actor you will use proxy class Celluloid::Method
to execute code through actor in sync or async way. Some libraries expects
that Method (Celluloid::Method) object will be respond to methods from
standard library Method.
Merge pull request #300 from LTe/support-for-other-methods

Celluloid::Method should respond to Method methods