add Closeable/Flushable interfaces

apps/sam/java/src/net/i2p/sam/SAMMessageSession.java

@@ -9,6 +9,7 @@ package net.i2p.sam;
  */
 
 import java.io.ByteArrayInputStream;
+import java.io.Closeable;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.Properties;
@@ -31,7 +32,7 @@ import net.i2p.util.Log;
  *
  * @author human
  */
-abstract class SAMMessageSession {
+abstract class SAMMessageSession implements Closeable {
 
     protected final Log _log;
     private I2PSession session;