#23 Failure if plan includes node removed from sites.xml

[Robert Adams]

If a node is removed from sites.xml and that node is
identified in a plan by nodeID, DSMTS throws and
exception and leaves temp files around. It will
eventually run out of memory.

One example of the failure is in
org.dsmt.dsmts.plans.ManualPlan.writeXML where it trys
to do a getHostname() on the return null from the
BlackBoard.