Generic uncaught exception handling

[RazzM13]

Apparently, cfn-lint circumvents NodeJS's default behaviour of returning an exit code of 1 when an uncaught exception bubbles up to the event loop.

Steps to reproduce:

1. Trigger an uncaught exception (e.g. attempt to validate a non-existing file).
2. Check the exit code.
   validate.log

[RazzM13]

This is probably the root cause of #121. After a bit of investigation I believe that the culprit is the winston logger and the most likely fix is to set exitOnError to true in the logger.ts file.