Edited Issue: Multiple cookies and Set-Cookie headers [288]

Current implementation has issue with cookies.

When you invoke

response.Headers.Add("Set-Cookie", "a=b;Path=/;");
response.Headers.Add("Set-Cookie", "c=d;Path=/;");

Actually only one Set-Cookie header is sent with comma-separated cookies.
Set-Cookie:a=b;Path=/;,c=d;Path=/;,e=f;Path=/;

But no browsers understand such syntax (it's against RFC6265).

And actually only first cookie is set.

For more details and code examples see
http://stackoverflow.com/questions/11533867/set-cookie-header-with-multiple-cookies