refs #382, reviewed audio context handling

* only init QDbusServer for P2P
* changed init order of contexts in runtime
* use "fake" signal to call setComVoiceRooms (remote in GUI)
* added slot to change voice room callsign
* used "org.swift" instead of "net.vatim" (just style)
* used const QString for serviceName
* added correct copyright header (just style)

src/blackcore/context_audio.cpp

@@ -23,7 +23,7 @@ namespace BlackCore
         case CRuntimeConfig::LocalInDbusServer:
             return (new CContextAudio(mode, runtime))->registerWithDBus(server);
         case CRuntimeConfig::Remote:
-            return new CContextAudioProxy(BlackCore::CDBusServer::ServiceName, conn, mode, runtime);
+            return new CContextAudioProxy(BlackCore::CDBusServer::ServiceName(), conn, mode, runtime);
         default:
             return new CContextAudioEmpty(runtime); // audio not mandatory
         }