ACCUMULO-1231 use system credentials all the time

git-svn-id: https://svn.apache.org/repos/asf/accumulo/branches/1.5@1463553 13f79535-47bb-0310-9956-ffa450edef68
ACCUMULO-1231 use system credentials all the time

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1463561 13f79535-47bb-0310-9956-ffa450edef68