Fixes issue #187.

We now add source and destination to flow spec instances.

We used to create the flowspec instance on demand when creating
end-to-end flow instances.
Later Lutz added initialization of FlowSpec instances during component
instance creation, but did not set the source and destination.

MinYoung's patch recognizes the same thing.
Fixed issues with latency analysis. More confusion about when to use
MilliSec vs. MicroSec.  (MS vs. US).
Renamed additional methods to reflect assumed unit in name.