HBASE-11053-Change DeleteTracker APIs to work with Cell (Ram)

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.98@1590219 13f79535-47bb-0310-9956-ffa450edef68
HBASE-11054-Create new hook in StoreScanner to help user creating his own delete tracker (Ram)

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.98@1590221 13f79535-47bb-0310-9956-ffa450edef68