ACCUMULO-1334 add disk usage to the API

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1478175 13f79535-47bb-0310-9956-ffa450edef68
ACCUMULO-1370 ignore configuration files for rat check

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1478176 13f79535-47bb-0310-9956-ffa450edef68