Handle -s specifications when callers use _init
Merge pull request #52 from ethomson/init_shutdown

Handle -s specifications for tests
Merge pull request #51 from transcriptic/master

Call save_cache on self not instance created in if __name__ == "__main__": ...
OptionParser does not handle -xabc -xcdf (multiple of same option) so multiple exludes did not get through.  Switch to ArgumentParser.