Allow classloader to be passed into EMS advanced properties

Removes an unnecessary cast

Example:

ClassLoader ccl = Thread.currentThread().getContextClassLoader();
Properties p = new Properties();
p.put(JMXConnectorFactory.DEFAULT_CLASS_LOADER, ccl);

ConnectionSettings connectionSettings = new ConnectionSettings();
connectionSettings.setAdvancedProperties(p);
ConnectionFactory connectionFactory = new ConnectionFactory();
ConnectionProvider connectionProvider = connectionFactory.getConnectionProvider(connectionSettings);