ACCUMULO-1282 ignore permission problems getting disk usage information

git-svn-id: https://svn.apache.org/repos/asf/accumulo/branches/1.5@1468995 13f79535-47bb-0310-9956-ffa450edef68
ACCUMULO-1282 ignore permission problems getting disk usage information

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1468997 13f79535-47bb-0310-9956-ffa450edef68