fix per http://twiki.ntp.org/bin/view/Support/JavaSntpClientDev (thanks duck!)

this may have caused some clock skew problems on the deployed 0.3.1.1, so we'll get this deployed asap

apps/time/java/src/net/i2p/time/NtpMessage.java

@@ -384,7 +384,7 @@ public class NtpMessage {
         // low order bits of the timestamp with a random, unbiased
         // bitstring, both to avoid systematic roundoff errors and as
         // a means of loop detection and replay detection.
-        array[7] = (byte) (Math.random()*255.0);
+        array[7+pointer] = (byte) (Math.random()*255.0);
     }