HBASE-8024 Make Store flush algorithm pluggable

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1475870 13f79535-47bb-0310-9956-ffa450edef68
HBASE-5930. Limits the amount of time an edit can live in the memstore.

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1475872 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd