Fix direct calls behavior.

 - Bug 1034068 — Trying to call a non-registered identity
 - Bug 1034537 — Trying to call an array of identities is not working as expected
Yes it is safe to use the Host, because it is already configured by the HTTP Protocol and it is good to let the user choose from which name it is coming. Also the nginx server is already configured to let pass only certain names.

We should definitly let the Amazon load balancer make the round robin but this is another subject :)