trunk-tracking: update to 1.6.29.2

* ConsoleHandler now takes a RewriteOptions
* Console needs ports to override the statistics handler path.  Before the
  console just assumed statistics were available at /mod_pagespeed_statistics.
* The "nostore" test fails.  I've marked this as an expected failure and will
  fix it in a followup.
* downstream_cache_purges stat was renamed to downstream_cache_purge_attempts
* Proxying tests with gstatic no longer use 1.gif but are switched to
  pss-architecture.png.
* DownstreamCacheLifetimeMs option was removed.
Merge pull request #419 from pagespeed/jefftk-update-trunk-tracking

trunk-tracking: update to 1.6.29.2