Include StructureStatusGoal

Add the option to apply a minimum on/off goal for the status of a station. This is based on the minimum on/off goal for pumps but this time the station status is the sum of the status of pumps. and therefore on status ranges from 1 to # of pumps, off is still 0. The user should provide minimum on/off times for the station in the same way as they do for the pumps. Again this is a goal not a hard constraint. We need to add the option for hard constraint here (issue in JIRA), to do so function range should be smaller.

PumpStatusGoal is replaced by StructureStatusGoal which accepts Pump or PumpingStation objects. PumpStatusGoal may still be used