Fix (S)FTP gateway samples in docs for expression

SO: http://stackoverflow.com/questions/39293574/how-to-configure-sftp-outbound-gateway-using-java-config

src/reference/asciidoc/ftp.adoc

@@ -888,7 +888,8 @@ public class FtpJavaApplication {
     @Bean
     @ServiceActivator(inputChannel = "ftpChannel")
     public MessageHandler handler() {
-        FtpOutboundGateway ftpOutboundGateway = new FtpOutboundGateway(ftpSessionFactory(), "ls");
+        FtpOutboundGateway ftpOutboundGateway =
+                          new FtpOutboundGateway(ftpSessionFactory(), "ls", "'my_remote_dir/'");
         ftpOutboundGateway.setOutputChannelName("lsReplyChannel");
         return ftpOutboundGateway;
     }

src/reference/asciidoc/sftp.adoc

@@ -976,7 +976,7 @@ public class SftpJavaApplication {
     @Bean
     @ServiceActivator(inputChannel = "sftpChannel")
     public MessageHandler handler() {
-        return new SftpOutboundGateway(ftpSessionFactory(), "ls");
+        return new SftpOutboundGateway(ftpSessionFactory(), "ls", "'my_remote_dir/'");
     }
 
 }