Changed l4id_t type to unsigned integer. Expanded task_ids to have cid

Task ids are now unsigned as the container ids will need to be encoded
in the id fields as well.

For requests who require even more comprehensive id input, (such as
thread creation) also added is the container id so that threads
_could_ potentially be created in other containers as well.

src/api/syscall.c

@@ -48,6 +48,7 @@ int sys_getid(struct task_ids *ids)
 	ids->tid = this->tid;
 	ids->spid = this->space->spid;
 	ids->tgid = this->tgid;
+	ids->cid = this->container->cid;
 
 	return 0;
 }