Add tests for 1xx, 204 and 304 responses to response_test.rb

In response_test.rb, we haven't had a test to make sure that

1) these responses don't have a message-body as described in RFC7231[1]

2) 1xx and 204 responses must not have a Content-Length header field
   as described in RFC7230-section3.3.2[2]

[1] https://tools.ietf.org/html/rfc7231
[2] https://tools.ietf.org/html/rfc7230#section-3.3.2

Even though our implementation doesn't allow users to send
a Content-Length header field in a 304 response, sending the
header field is valid as mentioned in RFC7230-section3.3.2[2].
So I've decided not to test whether or not a 304 response has
the header.

The citation from the section is as follows;
```
A server MAY send a Content-Length header field in a 304 (Not
Modified) response to a conditional GET request (Section 4.1 of
[RFC7232]); a server MUST NOT send Content-Length in such a response
unless its field-value equals the decimal number of octets that would
have been sent in the payload body of a 200 (OK) response to the same
request.
```

0 files changed, 0 insertions, 0 deletions