Fallback to object.method when necessary …

Certain strangely built proxy objects can mess with out "no tampering"
method lookup code, in those cases we'll try to perform the lookup the
old fashioned way.
Changelog for #90
[skip ci]
Merge pull request #90 from rspec/fallback_to_object_method_when_necessary

Fallback to object.method when necessary
WIP fix for kw args issue