refs #9048 removed unused header from the BoxController.h
refs #9048 Coverity bug in ConvToMDEventsWS

https://scan6.coverity.com:8443/reports.htm#v29240/p10083/fileInstanceId=11025021&defectInstanceId=3876993&mergedDefectId=528900
It looks like real resource leak, fixed by wrapping the thread scheduler into unique pointer.