Check the response headers for the response_code if not passed into the options.
Reject headers when computing redirections if those headers have a 2xx response, because they correspond to proxy responses.
Add cached? method for response, it returns true when response is taken from cache
Fix typo in Caching section of README.md
Move response cache logic to cacheable module
Add default maxredir 50. This is the way cUrl does it.

Fixes https://github.com/typhoeus/typhoeus/issues/337.
Remove old pending spec which served as a todo.
Use self.method instead of extend self.
allow rubinius to fail.
add fast_finish.
update documentation.
Dreaming of an `on_body` API for response streaming.
on_body is not marshallable.
Pass the on_body callback to the Ethon::Easy.
Loosen the requirement on response.body
Make the response available to on_body.
Adding note about clearing stubs between tests.
Clarifying that rspec configuration block should be placed in a spec_helper.rb file.
spelling.
Update with new ethon on_body callback API.