aggregator tested and working

passes simple tests after bug fix. needs more testing though
Merge branch '1.1_demand_zone' into jim_1.1_demand_zone
bug fix - source clock test was broken

… and Aggregator now knows how to explain itself to stream
Merge branch '1.1_demand_zone' into jim_1.1_demand_zone
fixes virtual overrides
virtual override (again)
configfactory gives aggregator a clock

… because aggregator needs it.
also: config file format changes. see sampletown_realtime.cfg for
example syntax
Merge branch '1.1_demand_zone' into jim_1.1_demand_zone