ACCUMULO-1516 deprecate Constants.NO_AUTHS in favor of Authorizations.EMPTY; update usage throughout code, cleaning up some unnecessary javadoc/non-javadoc comments along the way

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1493250 13f79535-47bb-0310-9956-ffa450edef68