HBASE-10062. Reconsider storing plaintext length in the encrypted block header

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1547373 13f79535-47bb-0310-9956-ffa450edef68
HBASE-10065. Stronger validation of key unwrapping

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1547374 13f79535-47bb-0310-9956-ffa450edef68