Added isOpen method

Author: eduard93

src/isc/rabbitmq/API.java

@@ -148,6 +148,11 @@ private GetResponse readMessage(String[] msg) throws IOException {
 
     }
 
+    public Boolean isOpen()
+    {
+        return _connection !=null ? _connection.isOpen() : false;
+    }
+
     public void close()throws Exception {
         _channel.close();
         _connection.close();