Fix cookies on multiple page

[j0k3r]

It was the case for golem.de, the cookie wasn't properly send to the next page (might be a bug in the cookie jar not properly retrieving previous defined cookies).

Fix j0k3r/graby-site-config#48

[coveralls]

Coverage increased (+0.5%) to 95.611% when pulling e3504a5 on fix/cookie-multiple-pages into a7aecce on master.

[Kdecherf]

Didn't check in depth but we may need to add a test to ensure that we don't leak cookies if the next page is not on the same domain. What do you think?

[j0k3r]

That's a good question, this shouldn't happen so much.
Should we add the cookie in the cookie jar instead so it'll be checked later in the foreach?

[j0k3r]

I've checked and cookies we are re-injecting are only those which are defined in site config, so there shouldn't really contains sensitive data?
Otherwise I don't know how to fix the leak because at the point where we should check it, we don't know the host associated to cookies which are in the headers.