Decide what to do about links that don’t expose content-length or transfer-encoding

[tusbar]

Some links (like https://api.sandre.eaufrance.fr/referentiels/v1/dc.csv?compress=true) do not expose content-length or transfer-encoding headers, so hasBody from type-is returns false.

Such links do not respect http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.3, so it’d probably be best if they added the headers instead of us trying to figure if there is in fact a body.

//cc @jdesboeufs