ACCUMULO-1048 cleaned up master lock acquisition

git-svn-id: https://svn.apache.org/repos/asf/accumulo/branches/1.5@1459990 13f79535-47bb-0310-9956-ffa450edef68
ACCUMULO-1048 cleaned up master lock acquisition

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1459993 13f79535-47bb-0310-9956-ffa450edef68