ACCUMULO-1330 patch from Corey Nolet which specifies units in du help command

git-svn-id: https://svn.apache.org/repos/asf/accumulo/branches/1.5@1471390 13f79535-47bb-0310-9956-ffa450edef68
ACCUMULO-1330 patch from Corey Nolet which specifies units in du help command

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1471569 13f79535-47bb-0310-9956-ffa450edef68