cache: Improved hash function in cache

Use last 8 bytes in addition to first one. Otherwise all keys for
specific shard comes to single cache object.
cache: Changed format of cache logs

Write log once per action

Conflicts:
	cache/slru_cache.cpp
cache: Added more logs to resize operations

Conflicts:
	cache/slru_cache.cpp
Merge pull request #303 from euroelessar/master

Cache improvements