deal with null peer (used by the SubmitMessageHistoryJob to bw limit the history)

current 0.3.2 throws an NPE which causes the submitMessageHistory functionality to fail, which isn't really a loss since i send that data to /dev/null at the moment ;)
(but you'll want to router.keepHistory=false and router.submitHistory=false)
this'll go into the next rev, whenever it comes out
(thanks ugha!)

router/java/src/net/i2p/router/transport/BandwidthLimitedInputStream.java

@@ -32,7 +32,8 @@ public class BandwidthLimitedInputStream extends FilterInputStream {
         super(source);
         _context = context;
         _peer = peer;
-        _peerSource = peer.getHash().toBase64();
+        if (peer != null)
+            _peerSource = peer.getHash().toBase64();
         _pullFromOutbound = pullFromOutbound;
     }