address: enable events and expose address flags (bnc#889981)

- Added address,prefix,nduseropt event trace functions to log the data in debugX modes.
- New addresses were not visible in ifstatus, because addresss events were not enabled
  in wickedd (unlike in dhcp6)  and dbus were showing a snapshot only.
- Enabled also IPv6 RA prefix and rdns update events in wickedd.
- Exposed address flags via dbus and show them in ifstatus without to filter out duplicate
  or tentative addresses.
- In dhcp6 auto mode, recheck the RA managed/other-config flags on each device-change
  and try to start when they're set as we already do on each prefix event.