MINOR: http: add support for "httponly" and "secure" cookie attributes

MINOR: http: add support for "httponly" and "secure" cookie attributes

   httponly  This option tells haproxy to add an "HttpOnly" cookie attribute
             when a cookie is inserted. This attribute is used so that a
             user agent doesn't share the cookie with non-HTTP components.
             Please check RFC6265 for more information on this attribute.

   secure    This option tells haproxy to add a "Secure" cookie attribute when
             a cookie is inserted. This attribute is used so that a user agent
             never emits this cookie over non-secure channels, which means
             that a cookie learned with this flag will be presented only over
             SSL/TLS connections. Please check RFC6265 for more information on
             this attribute.