Changed key-value separator to ':' for arguments to -o option, and made
default value '-' indicating stdout.
Basic support for saving workflow output to destination indicated by -o
argument.
Moved static methods from RestFlowTestCase to TestUtilities.
Updates to reflect move of static methods from RestFlowTestCase to
TestUtilities.
Replaced StandaloneActorTestCase with a general RestFlowCommandTestCase
for testing via RestFlow's command line interface.