adjusts how errors are handled

[bkendall]

Description

calling process.exit is an abrupt way to end the process. setting process.exitCode and allowing the process to naturally finish is a little better.

also, listening to uncaughtException isn't the best way to handle those types of errors - instead, uncaughtExceptionMonitor is there to handle our case where we need to handle them.

Scenarios Tested

• --open-sesame commands it knows and doesn't know
• hosting deploys that should succeed and fail