MB-100: record latency stats for reload phase

Change-Id: I101eb384afc55a708702cae565e212eac5b6952f
Reviewed-on: http://review.couchbase.org/26388
Reviewed-by: abhinav dangeti <abhinav.dangeti@gmail.com>
Tested-by: abhinav dangeti <abhinav.dangeti@gmail.com>