fix http state

[fogfish]

https://github.com/kfsm/htstream/blob/master/src/htstream.erl#L318

%% 2. If a Transfer-Encoding header field (section 14.41) is present 
%%    and has any value other than "identity", then the transfer-length 
%%    is defined by use of the "chunked" transfer-coding (section 3.6), 
%%    unless the message is terminated by closing the connection.

"unless" statement is not implemented.