Added follow_method option to avoid rewriting method as GET

Added a configuration parameter to help work with ambiguity between the [RFC-7231](http://tools.ietf.org/html/rfc7231#section-6.4) specification and the older [RFC-1945](http://tools.ietf.org/html/rfc1945#section-9.3) specification on `Location` following rewriting the request method as `GET`.

For example, `POST http://example.com` might `301` or `302` with `Location: https://example.com`. Rewriting as `GET` would make the follow-up request useless without preserving the `POST` method and data.