The number of total sources will no longer be tracked in real time, so
commented out displaying summary status messages.
Fixing up model tests now that total statistics will not be tracked in real
time.  Work in progress.
Created a new base test case class which deletes files in a directory
which are not set in the configuration as part of the test files.
Put it to use in the test_model_persistence and test_models test 
suites.
Created new events module to hold pub/sub ids.  Will expand it to 
encapsulate pubsub usage later.
Got all tests in test_models suite passing.
Moved test_models into the test_integration package.  Merged 
test_model_persistence into test_models.  Got these tests passing.
Fixed file locking test case.
Moved test_controllers to test_integration package.  Got test_controllers
passing.
WorkUnitProvider now skips over empty files.
Changed DirectoryCleaningTestCase method names so that they don't 
get interpreted as test cases by nose's default regex.
Removed no longer needed AstromWorkloadTest cases.  Removed 
unused AstromWorkload imports.
Removed redundant test cases.
Removed AstromWorkload class.
Source is no longer iterable.  Use get_readings method.
Got app running.
Quick fix for loading new images when moving to next work unit.
Application is basically functioning now.
Removed unused code in models.py