! can: enable redirection for any 307 responses

This is because the latest httpbis draft doesn't explicit state
anymore that a request should only be redirected for GET or HEAD
requests when 307 is received.

See https://tools.ietf.org/html/draft-ietf-httpbis-p2-semantics-25#section-6.4.7

Also, added a comment about 302 handling.