SMP shared memory cache stats were not collected.

SMP shared memory cache stats were not collected.

"Hot Object" stats were not reported for shared memory cache.

Mean disk object size stats were aggregated inaccurately for SMP.

Moved Store-related stats into a dedicated StoreStats class,
encapsulating memory cache-related (mem), disk cache-related (swap), and
global store (number of objects) stats. Used consistent naming scheme
and a common parent class to make memory and disk stats more alike.

Moved Store stats collection into corresponding Store classes rather
than forcing GetInfo() in stat.cc to know how to deal with all Store stats.