ACCUMULO-1125 delete distributed work queue task lock when task fails

git-svn-id: https://svn.apache.org/repos/asf/accumulo/branches/1.5@1451015 13f79535-47bb-0310-9956-ffa450edef68
ACCUMULO-1125 delete distributed work queue task lock when task fails

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1451019 13f79535-47bb-0310-9956-ffa450edef68