Refactor the StatsSnap task

Change-Id: I22c46bed3da65b022a76bf756715ff475bc70617
Add the iomanager

Change-Id: I0766f6f9ad597c35f85f9af69494873b329ac193
Moved the VBucketDelete Task

Change-Id: I96041520870eef0dbd4c7714c9a3eaac7e658f08
Fix all of the bugs related to previous work

Change-Id: Ib8ade98fec1fc768df48f25a0d5d83a44b69ca4e