- ensure to announce airtunes before airplay via zeroconf (makes it more likely that ios7 clients detect us correctly at the first shot)
- add method to reannounce already published services
- reannounce airplay service every 10 secs (fixes ios7 clients not detecting us when their wlan was asleep or they saw the airplay announcement before the airtunes annoncement)
- add doForceReAnnounce