Testcommands should handle exception signals (2)

Many testrunning commands have 3 defined signals,

• 0 - everything ran, tests passed
• 1 - everything ran, test condition failed
• 2 - exception during test execution, testrunner may have bailed, fataled, or otherwise broke
• 3->255 Some other catastrophic failure (core dump etc)

Currently testrunner handles 2 as a 3->255 situation. It should probably return a better error message in the case that the underlying testing tool knows what kind of error it is.