Cookies are comma separated according to rfc2109 4.2.2

The syntax for the Set-Cookie response header is

    set-cookie      =       "Set-Cookie:" cookies
    cookies         =       1#cookie
    cookie          =       NAME "=" VALUE *(";" cookie-av)
    NAME            =       attr
    VALUE           =       value
    cookie-av       =       "Comment" "=" value
                   |       "Domain" "=" value
                   |       "Max-Age" "=" value
                   |       "Path" "=" value
                   |       "Secure"
                   |       "Version" "=" 1*DIGIT

For example (2 cookies, with attribute value pairs):
USER=john;domain=.example.com;path=/, PREFS=123123;path=/

This commit is not a full cookie store implementation as the path
should be compared against the request path to determine if the
cookie should be transmitted to the server, along with expired
cookies should be removed.