It seems that Fakeweb doesn't like Mechanize agent's read_timeout= method (http://stackoverflow.com/questions/7137467/ruby-fakeweb-error-if-a-mechanize-agents-read-timeout-is-called)
Add #read_timeout and #continue_timeout to match Net::HTTP API

Net::HTTPSession objects support #read_timeout and #continue_timeout setters and getters.  When using fakeweb via VCR, code using these attributes raise errors (NoMethodError: undefined method).  

Adding these attributes resolve the issue.
Merge pull requests #28 (syborg) and #38 (trevorrowe)

This adds the timeout methods from Net::HTTP's socket proxy (Net::BufferedIO)
missing from our fake (StubSocket), fixing that Net::HTTP#read_timeout= and
Net::HTTP#continue_timeout= would raise NoMethodErrors when called after a
Net::HTTP object has handled a first fake request (i.e. after StubSocket has
been injected).
Fill in test coverage for #read_timeout=, etc. from 0deafd2aa8
Make sure the methods in our fake match the user's version of Net::HTTP

Specifically, this ensures that we won't add #continue_timeout= to rubies
that don't have it -- it was added to Net::HTTP in 1.9.3.