I2P fixes for out-of-order nonce counts.
   Based on DigestAuthenticator in Jetty 7.6.10.
   Includes the nonce count verification code from Tomcat 7.0.35.
   ref: http://jira.codehaus.org/browse/JETTY-1468 which was closed not-a-bug.
   ref: https://bugs.eclipse.org/bugs/show_bug.cgi?id=336443 in which the
   Jetty implementation was introduced.