File fetcher tests
IMPLEMENTING - issue GDP-598: RFC Real Time Archive Builder 
https://internal.cida.usgs.gov/jira/browse/GDP-598

Test for input file aggregation. Failing at the moment.
IMPLEMENTING - issue GDP-598: RFC Real Time Archive Builder 
https://internal.cida.usgs.gov/jira/browse/GDP-598

Aggregation fixed.  Note that we have to do some extra work to get
message groups expired at the end of the run.