Log the end of the token which varies by token

Turns out the beginning of the token is largely the same
and not very meaningful in a log.  Instead log the end
of the token which should be different between legitimate
tokens.

Change-Id: I805965cc67d75ec975d2d26951fa9396e5397ede

java/monasca-common-middleware/src/main/java/monasca/common/middleware/HttpAuthClient.java

@@ -101,10 +101,10 @@ public class HttpAuthClient implements AuthClient {
           instream = entity.getContent();
           instream.close();
           //
-          // Don't log the whole token, just the first ten characters
+          // Don't log the whole token, just the last ten characters
           //
-          throw new AuthException("Authorization failed for user token beginning with: "
-             + token.substring(0, 10));
+          throw new AuthException("Authorization failed for user token ending with: "
+             + token.substring(token.length() - 10));
         }
 
         if (code != 200) {