OOZIE-1600 map-reduce actions without configuration section in workflow.xml throws "IllegalArgumentException: element cannot be null" (bowenzhangusa via rkanter)

git-svn-id: https://svn.apache.org/repos/asf/oozie/trunk@1538845 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk