rh #1025371 reports a crash in handle_ip_config_timeout() because
nm_device_wifi_get_activation_ap() did not return any access point
(line nm-device-wifi.c:3105).

In order to fix this, the whole handling of get_activation_ap vs.
current_ap was reworked and cleaned up.

This also fixes a memory leak in line nm-device-wifi.c:2111.

Also rename the functions get_active_ap (to find_active_ap) and
set_active_ap (to set_current_ap), because these two functions were not
getter/setter for an 'active_ap' property (as would be expected from the
previous name).

Also ensure, that a fake AP is never in the list of valid APs without
also being the current_ap. Whenever we reset a fake current_ap, the AP
gets removed.

https://bugzilla.redhat.com/show_bug.cgi?id=1025371



Signed-off-by: Thomas Haller <thaller@redhat.com>