Cache accumulators for 'popular entries'

[nicoloboschi]

JIRA: https://dev.blazingcache.org/jira/browse/BLAZ-15

Reporter: eolivelli @eolivelli

The idea is to have some node (client) which accumulates entries sent from other clients.

For instance an "acccumulator" could periodically ask the CacheServer for the most popular entries and issue fetchs for them in order to load the local cache.

This strategy would help cases in which a "popular entry" gets lost during a failure of many nodes in the cluster