Debugger: Store the version info of debug service plugins

Change-Id: I7cd73c5c4148929fa0a1d60d33fe16357f8c3705
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>

src/libs/qmljsdebugclient/qdeclarativedebugclient.h

@@ -89,7 +89,7 @@ public:
     ~QDeclarativeDebugClient();
 
     QString name() const;
-
+    float serviceVersion() const;
     Status status() const;
 
     virtual void sendMessage(const QByteArray &);