Added cmd line arg "seek_secs" to perform a singled time based seek.  Got rid of unused query cmd line arg.  Clean up logic in perform_test_rate_change() since it always does a query and a seek so no need for flags.
Merge pull request #5 from cablelabs/seek-secs-added

Added cmd line arg "seek_secs" to perform a singled time based seek.  Go...