Add Tiny LFU Cache Admission Policy to Cache about ristretto

[ben-manes]

HashDoS protection:
https://github.com/ben-manes/caffeine/blob/91eec88be93f16549ce82dd2f17959fd8eba75dd/caffeine/src/main/java/com/github/benmanes/caffeine/cache/BoundedLocalCache.java#L749-L773

CountMin4:
https://github.com/ben-manes/caffeine/blob/master/caffeine/src/main/java/com/github/benmanes/caffeine/cache/FrequencySketch.java

W-TinyLfu (simulator):
https://github.com/ben-manes/caffeine/blob/master/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/sketch/WindowTinyLfuPolicy.java

[ben-manes]

I'm not sure if @karlmcguire is involved in this effort, but he's been cranking out a nice looking implementation. Lots more to do (e.g. adaptivity) but fyi if disjoint work.

https://github.com/xba/tinylfu