Added BloomCache classes

* Implemented a version of BloomCache using Redis
* Added a BloomCheckTitleHasLogs handler class for avoiding
  slow logging table queries when large amounts of 404 pages
  are viewed (by various web crawlers at the moment).

bug: 67439
Change-Id: I26e5034755e3a7208a45991b1cf2f12467679cc1
Merge "Added BloomCache classes"