ACCUMULO-1276 improved password generation

git-svn-id: https://svn.apache.org/repos/asf/accumulo/branches/1.5@1468201 13f79535-47bb-0310-9956-ffa450edef68
ACCUMULO-1276 improved password generation

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1468205 13f79535-47bb-0310-9956-ffa450edef68