Correct allowed failure setting
Add ModuleMethods#original_instance_method

The public interface of adamantium infected classes now allows to
receive the original unbound method instance via
Class#original_instance_method(method_name)
Adjust flay score
Refactor memoized_method registratio to use default proc
Remove testing under 1.8
Use source location as equalization criteria for rbx

RBX equalizes UnboundMethod instances via identity
Use Hash#[] to trigger default proc
Merge pull request #16 from mbj/store-original-method

Store original method