avahi: Service hostname must contain, resolvable fqdn 

Service registred via avahi dbus api must contain fully resolvable FQDN with .local append to its value. Service which doesn't not abide to this rule won't be resolvable.

Test case:
```
# avahi-browse -t -v -r _mopidy-http._tcp.
Server version: avahi 0.6.31; Host name: shramba.local
E Ifce Prot Name                                          Type                 Domain
: Cache exhausted
+   eth0 IPv4 Mopidy HTTP server on namizni                 _mopidy-http._tcp    local
=   eth0 IPv4 Mopidy HTTP server on namizni                 _mopidy-http._tcp    local
   hostname = [namizni.local]
   address = [192.168.1.29]
   port = [6680]
   txt = []
: All for now
```