[#19] Fix VerifiedDouble.of_instance(class_name, method_stubs={})
  with method_stubs hash where the double is an value of an expectation
  should not interfere with the method signature recording of the expectation.
RecordedMethodSignature#initialize should handle setting of #stack_frame.
[#19] Add SimpleDouble#build_recorded_method_signature.
  Refactors VerifiedDouble.of_instance(*args) and RecordedMethodSignatureRegistry#add_method_signature.