Added tests for -i option assigning literal values to workflow inputs.
Refactored test to elimate error messages printed to stderr.
Fixed bug in test.
runRestflowWithArguments() now takes a String[] argument.
Added methods for accessing individual input and output values.
ConstantSource now accepts and can emit null values.
Moved and renamed number test workflow.
Renamed test of command line input feature and added a test workflow for
its use.