Print uncaught exceptions to the console before exiting.  This will display errors from async code in tests and commands.
Merge branch 'featureLogAsyncErrors' of https://github.com/joel-airspring/nightwatch into joel-airspring-featureLogAsyncErrors
adding the finishCallback into the process listener so that we can stop selenium as well when there's an uncaught exception
Merge branch 'joel-airspring-featureLogAsyncErrors'