Open-uri preventing redirects from https to http

Because it assumes it's insecure. That's quite annoying and should be configurable.

• http://www.ruby-forum.com/topic/1111884

def OpenURI.redirectable?(uri1, uri2)
  true
end

This monkey-patch fixes the issue and remove the check.

A bug exists for the stdlib http://bugs.ruby-lang.org/issues/859 but fixes just the other way round.