Some fixes found during testing with remote black core (different computer)

* Allow anonymous access for P2P
* Fixed sound settings flags, if empty string is saved in settings
* Fixed metadata registration

src/blackmisc/blackmiscfreefunctions.cpp

@@ -104,6 +104,7 @@ void BlackMisc::Network::registerMetadata()
 void BlackMisc::Settings::registerMetadata()
 {
     CSettingsNetwork::registerMetadata();
+    CSettingsAudio::registerMetadata();
 }
 
 /*