added missing TRACE_OFF level

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1616526 13f79535-47bb-0310-9956-ffa450edef68
added simple trace API to proton-j

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1616527 13f79535-47bb-0310-9956-ffa450edef68