Fixes for call-collect and admit/deny directives.

The switch from am_policy_hub to policy_server was only partially done, which lead to breakage.
Completion of cf-serverd's hand-off of call-collect connections to cf-hub required more careful handling.
The rewrite of ServerEntryPoint() makes it easiest to review (at least its file) one commit at a time.
@pasinskim: we can do this later, but if you tell me now I can do it now instead ;-)