Add basic stats for strongly consistent operations

Consistent gets/puts now correctly increment vnode_gets/vnode_puts the
same as normal gets/puts. Prior to this commit, gets incremented the
relevant stat but puts did not.

Consistent operations now maintain per-operation stats that are similar to
the node/FSM stats for normal gets/puts. This includes operation counts,
latency percentiles, and object size percentiles.
Add stat recreation code
Merge branch 'develop' into feature/consistent-stats
Merge pull request #981 from basho/feature/consistent-stats

Add basic stats for strongly consistent operations

Reviewed-by: engelsanchez