Add new SmokeRunner and associated SmokeCommand

Provides a harness for smoke testing, the smoke runner runs an operation
mix once through and reports a pass/fail depending on whether any
operations failed
Add command line scripts for invoking smoke tests
Add smoke commands to ReadMe, standardize exit code constants

This commits adds notes about the smoke command to the ReadMe.  It also
updates the command code to use a standardized set of constants for exit
codes so they are consistent across all commands