Return nonzero exit status code in case of a test failure

[munkius]

Nodeunit always returns an exit status 0, disregarding if there are failing tests. This troubles my continuous integration system (Jenkins) which performs a build and runs my tests. Jenkins verifies if the commands it executes in the build return a nonzero status code, which means the execution encountered problems. Now I need to grep the output to check for failures and mark my build as failed.

I'm working on a patch for this (https://github.com/munkius/nodeunit)