Cleanup and semantic changes

Reworked a lot of things.

 - refactored all the things to reduce code duplication and enhance testability
 - changed siphash to use a null-byte string for consistency with everything else we use siphash for
 - don't write out duplicate consolidated streams when we don't need to
 - don't include flavor ID in the identifier of all metrics
 - cut down sourcedicts substantially, don't include 
  - flattened resource metadata 
  - flavor data
 - add more consolidated (pollster) instance metrics
  - instance_vcpus
  - instance_ram