fsm: tune ni_ifworker_by_ifindex

- rename to ni_fsm_ifworker_by_ifindex
- add param validity check
fsm: Add object_path parsing functions

- __ni_fsm_dbus_objectpath_to_ifindex
- __ni_fsm_dbus_objectpath_to_name
fsm: tune ni_fsm_ifworker_by_object_path

This function looks also for not refreshed
workers by their name.
Revert "server: no unrequested device-ready events (bnc#871135)"

This reverts commit f44606d1678d2a7411b7b27c20fa166214a8ce02.
fsm: wait for existing configration workers (bnc#876855, bnc#880515)

When interface shows up late (but the configuration is present)
we wait for it until WAIT_FOR_INTERFACES timeout.
Merge pull request #301 from pwieczorkiewicz/fsm_tweaks
Merge pull request #302 from pwieczorkiewicz/late_ifaces